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S0022311520310722
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Ferritic martensitic ODS steels are one of the candidate structural materials for future Gen IV nuclear fission and fusion reactors . The dependence of fracture toughness on microstructure was investigated by comparing three 9Cr ODS EUROFER steels manufactured through different thermo mechanical processing routes . Quasi static fracture toughness testing was performed with sub sized C specimens and microstructural characterization was carried out using scanning electron microscopy electron backscatter diffraction and transmission electron microscopy . It was found that at lower test temperatures the fracture toughness was primarily controlled by crack initiation at sub micron particles and by production of secondary cracks during fracture . At higher temperatures fracture toughness was predominantly controlled by the matrix ductility and the grain boundary strength with a relatively ductile coarse grained alloy demonstrating higher fracture toughness compared to high strength fine grained alloys . These results and discussion show that variations in thermomechanical treatments can produce significant differences in microstructure and fracture toughness behavior of ferritic martensitic ODS steels .
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Three 9Cr ODS EUROFER steels are compared with respect to microstructure and fracture toughness. Secondary cracking induced by residual ferrite improves fracture toughness at lower temperatures. Matrix ductility predominantly controls the fracture toughness at temperatures between 100C and 500C. Above 500C the grain boundary strength predominantly controls the fracture toughness. Variations in thermo mechanical history lead to significant differences in microstructure and fracture behavior.
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S0022311520310734
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Gaseous nitrogen is planned to be used as a seeding species to control the power flux in future fusion reactors with ITER like divertors . Nitrogen interacts with the first wall materials particularly with tungsten leading to sputtering and changes of chemical composition of the material . We use the molecular dynamics methods with a recently developed WN potential to analyze the mechanisms leading to these modifications . We performed the simulations of cumulative nitrogen irradiation runs of tungsten surface . The sputtering yields obtained in our cumulative runs are in good agreement with experimental data . We observe the decrease of the tungsten sputtering yield with nitrogen accumulation and determine the reasons for the observed trend . The cluster analysis reveals the composition of the sputtered particles suggesting the swift chemical sputtering process that occurs under the prolonged nitrogen irradiation of tungsten . We also observe and analyze the nitrogen saturation in the temperature range below the thermal stability limit .
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A newly developed W N potential based on Tersoff Brenner formalism was used. N accumulation reduces W sputtering yield by almost an order of magnitude. Approximately half of sputtered W atoms leave the surface as a WN molecule. Nitrogen saturation occurs by the growth of the N sputtering yield with the fluence. Nitrogen reflection coefficient remains constant during the accumulation.
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S0022311520310795
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Investigations on the morphology and phase equilibrium characteristics of corium were performed by a series of experiments in parallel with thermodynamic phase equilibrium analyses . Melting and solidification experiments were performed using corium consists of U Zr ZrO
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Experiments and thermodynamic analyses on morphology and phase equilibrium of corium. NUCLEA analysis results on U Zr O Fe system agreed well with the experimental findings. U U Zr ratio in good agreement whereas some dispersions observed in oxygen and steel compositions. Zirconium diboride phase trapped boron and mainly distributed in the metallic layer. Additional data required to improve for chemistry of corium containing B. C.
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S0022311520310874
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The adoption of Accident Tolerant Fuels in the US will only likely be realized through improving economics of existing commercial reactors . For this reason the Nuclear Energy Institute refers to such concepts as Advanced Technology Fuel . This work provides an insight into the performance of the fuel rod with high density uranium nitride pellet in silicon carbide composite cladding for a pressurized water reactor . The UN higher uranium density is one way to overcome the higher cost of SiC relative to current Zirconium based claddings . The material properties and irradiation behavior models of UN and SiC have been incorporated into the BISON fuel performance code . The modeling capability of BISON for SiC cladding is extended with irradiation creep and post irradiation thermal annealing models . The fuel rod performance during normal operation is evaluated across three fuel cycles with each cycle 24 month long . Selected accident scenarios include a large break loss of coolant accident and a station blackout accident where the potential effects of SiC irradiation creep and annealing rate are emphasized . This work motivates further experimental investigation on irradiation properties of dense UN SiC irradiation creep and nonisothermal annealing .
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Performance of full length UN SiC fuel rod is modeled during PWR normal operation. Performance of full length UN SiC fuel rod is modeled under PWR LBLOCA and SBO. SiC irradiation creep is not conducive to the fuel rod hermeticity under LBLOCA and SBO. Significant post irradiation annealing of SiC is unfavorable to the fuel rod hermeticity.
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S0022311520310886
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This work was part of a program begun in 2001 to develop advanced nuclear fuels originally as carriers for plutonium and minor actinides taken from spent commercial light water reactors so that the plutonium and minor actinides could be burned or transmuted in an accelerator or a fast nuclear reactor . A central part of these experiment programs has been the development of advanced fast reactor fuels because a fast reactor was considered the most efficient vehicle to transmute the actinide waste products and metallic fuels is a central focus of these tests . An experiment design was developed in which a thermal test reactor the Advanced Test Reactor was used to test small fuel pin prototypes by creating areas in the core shielded by cadmium filters to produce a largely epithermal and fast neutron spectrum environment in which the pins could be irradiated . The results of non fertile metallic fuel tests are presented here .
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Post irradiation examination of nonfertile metallic fuels no uranium tests are presented here for a series of compositions with and without minor actinides. Precision gamma scanning and fission gas release results are similar to other historical metal fuel experiments in fast reactors.
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S0022311520310916
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Partial slip fretting corrosion of Alloy 690TT comes up in the steam generator of a nuclear power plant in which the damage mechanisms are transformed as dissolved oxygen varies . In this work the coupling between the action of oxide particles sticking into the surface and the electrochemical corrosion caused severe pitting like damage which was enhanced by an increase in DO concentration increasing the wear volume . The initiation of fatigue cracking was controlled by the slip dissolution along with the competition between the film rupture rate and the repassivation rate as DO changes .
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Effects of dissolved oxygen DO on fretting corrosion of Alloy 690TT was studied. The wear volume wear width and depth were increased with increasing DO. The coupling between the physical and chemical effect caused pitting like damage. The pitting like damage was enhanced by an increase in DO. The fatigue cracking was controlled by slip dissolution and varied as DO changes.
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S002231152031103X
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The helium to vacancy ratio is a key factor related to the helium bubble hardening mechanisms induced by neutron irradiation in ferritic martensitic steels as advanced nuclear structural materials . According to the helium bubble hardening results in F M steel irradiated in the spallation neutron source the interactions between a 1 2 111 110 edge dislocation and helium bubbles with various sizes of 0.73.0nm in bcc Fe under irradiation temperatures and room temperature was investigated by using molecular dynamics simulation . The effect of various He V ratios in the ranges of zero to the highest He V ratios 1.854.0 of stable helium bubbles with no dislocation loop emission on the interaction mechanisms was analyzed . The results indicated that the critical resolved shear stress drops rapidly to a very low stress level and immediately bottoms out and rebounds to a very high stress level when the He V ratio increases from 1.0 to the highest He V ratio . The significant change of CRSS values is not only related to the climbing degree of dislocation after releasing but also related to the moment when the climb appears . A new repulsion mechanism of interaction between dislocation and bubble was proposed to elucidate the abnormal phenomena of the bottoming rebound of CRSS with a great climbing degree according to the repelling interaction between helium bubble and superjog of dislocation with both strong compressive stress field .
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The CRSS rapidly bottoms out and rebounds to a very high stress level when the He V ratio increases above 1.0. The significant change of CRSS values is not only related to the climbing degree of dislocation but also the moment when the climb appears. A new repulsion mechanism was proposed to elucidate the abnormal phenomena of the bottoming rebound of CRSS.
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S0022311520311041
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Using molecular dynamics simulation we investigate the dynamic evolution characteristics of He bubble and its effects on void nucleation growth and thermomechanical properties in single crystal Al during spallation . The evolution process of bubble includes four stages slow and independent expansion rapid and independent expansion deceleration expansion due to inter bubble interaction and merging and fast expansion after merging . The bubble radius time relation is approximately linear both before and after merging and the corresponding expansion rates are obtained . The mechanism of bubble expansion in solid metal under dynamic tension involves plastic deformation via dislocation nucleation and movement and temperature rising around the bubble . The growth toward neighboring bubble leads to the overlap of plastic deformation regions that promotes local melting . The flows of melted atoms along both normal and tangential directions of the two bubbles result in the thinning and breaking of the inter bubble ligament and thus bubble merging occurs . In melted metal the tension deformation under velocity gradient leads to bubble growth and coalescence . He bubble impedes the nucleation and growth of nearby voids and the expanded bubble absorbs grown voids when they contact . Such suppression enhances with the increase of bubble size or density while attenuates with the increase of shock strength . The number of nucleated voids is much lower and the average radius of voids is smaller for the sample with He bubbles in solid state . After melting the reduction in quantity gets smaller and the radius becomes a little higher due to the suppression on continuing nucleation of voids . The bubble behavior and its influence on void evolution result in the variation of spall mechanism the expansion and merging of He bubble play the leading role independent on shock strength bubble density or bubble size . The effects of He bubble on temperature and stress are also addressed .
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The expansion and merging of He bubble play a leading role in spall mechanisms of Al instead of void nucleation growth coalescence. The dynamic evolution process of He bubble involves four stages slow and independent expansion rapid and independent expansion deceleration expansion due to inter bubble interaction and merging and fast expansion after merging. The mechanism for bubble expansion growth in solid metal includes plastic deformation and local temperature rising the overlap of plastic deformation regions of adjacent bubbles and local melting promote the flow of inter bubble atoms leading to the thinning and breaking of inter bubble ligament and thus bubble coalescence merging . He bubble impedes the nucleation and growth of nearby voids and the expanded bubble absorbs grown voids when they contact. Such suppression enhances with the increase of bubble size or density while attenuates with the increase of shock strength.
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S0022311520311077
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Reduced activation ferriticmartensitic steels with different Cr contents were prepared to investigate the effect of Cr on the reheating cracking susceptibility in the weld heat affected zone . After HAZ simulation stress rupture tests were performed at 650750C corresponding to the post weld heat treatment temperature using a Gleeble simulator . Increasing the Cr content markedly reduced the rupture ductility resulting in an increase in the susceptibility to reheating cracking . This was attributed to the intergranular Cr enriched M
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Reheating cracking susceptibility in the weld HAZ of RAFM steels was evaluated. During rupture testing microvoids formed and grew along PAGB around M. carbides. Coarse intergranular M. carbides acted as initiation sites for reheating cracking. Size of intergranular M. carbide increased with an increase in Cr content. Susceptibility to reheating cracking increased with an increase in Cr content.
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S0022311520311089
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Genetic algorithm was applied to search the energy minimization configuration of vacancy clusters in Fe . Molecular statics calculations and dynamics annealing relaxation were employed to calculate the formation and binding energies of vacancies and 3D vacancy or vacancy hydrogen clusters as well as 2D vacancy or vacancy H clusters on and planes . Our calculations show that vacancies prefer to form 3D clusters and vacancy dislocation loops are difficult to form while vacancy H clusters prefer to shape into 2D clusters especially on planes . Since H prefers the directional bonding a vacancy cluster with H atoms tend to form a vacancy dislocation loop with its slip direction along the 100 direction and on the habit plane . Our results are consistent with the experimental observations and provide a possible mechanism for the formation of vacancy dislocation loops in Fe . Furthermore we have also explored how dislocation loops trap self interstitial atoms vacancies and H atoms . It is of interest to note that H atoms strongly bound to
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A possible mechanism for the formation of vacancy dislocation loops in Fe is proposed. Vacancy NH clusters prefer to shape into 2D clusters especially on 211 planes. The presence of H can greatly promote the growth of vacancy dislocation loops.
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S0022311520311156
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To explain the room temperature formation of He bubbles in SiC we present the influence of mono and di vacancies on the migration behavior of He atoms in the 6H SiC . The solution energy of He atoms inserted at different interstitial sites around vacancies is calculated via density functional theory . The results show that single carbon vacancy and silicon vacancy can reduce the solution energy of a He atom within the 4
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The influence of mono and di vacancies on the migration of He atoms was studied. A V. could reduce the solution energy of He atoms within the 4. NN site. One vacancy provided a circular migration channel with a radius of 2 for He atoms. The high energy barrier hindered the dissociation of He atoms in vacancies. The vacancies assisted migration of He atoms favored the formation of He platelets.
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S0022311520311168
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In a highly irradiated reactor pressure vessel solute Mn Ni and Si atoms gather to form nanometer sized microstructures generally called MNS clusters . MNS often gather with Cu rich precipitates which can form in RPVs following lower dose irradiation . In this study surveillance specimens provided from four nuclear power plants in Japan were analyzed using three dimensional atom probe tomography and the nature of the solute enrichment was carefully compared . When analyzing the chemical composition of each cluster a clear negative correlation was found between Si and Cu in all materials but conversely Mn was likely present in clusters with a high Cu concentration . Moreover in a boiling water reactor material with high Cu the ratio of MNS was shown to be similar to that of the
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Chemical compositions of solute atom clusters in surveillance materials from four nuclear power plants were compared. The balance of Mn Ni Si in solute clusters in a BWR material is similar to that of the. phase. Relative Si concentrations in solute clusters in PWR materials are higher than the Si concentration in the G phase. This suggests the contribution of radiation induced segregation of Si. The catalyst effect of Cu precipitates on the gathering of Mn and Ni may assist in Mn Ni Si cluster formation.
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S002231152031117X
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The plasma facing unit of ITER divertor is repeatedly exposed to high heat flux and a reliable heat removal capability is crucial for its adequate performance . The cyclic high heat flux test that has been conducted to evaluate the reliability of PFU reveals that the surface modification and macro crack formation in W monoblock which is the plasma facing material may hinder the operation of fusion reactors . Therefore optimization of both manufacturing technology and material development is necessary for reliable operation . In this study we investigate the dependence of material properties on the surface modification and macro crack formation in W monoblocks . W monoblocks manufactured by two different suppliers were examined and the results of cyclic HHFT revealed that the heat removal capability was not degraded in all the examined W monoblocks . Further it was observed that the W monoblock exhibiting characteristic grain structure and tensile property suffered less surface modification without macro crack formation due to cyclic heat loading .
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Effect of cyclic heat load and material properties on W monoblock is examined. W monoblocks manufactured by two different suppliers ALMT and NSCM are compared. The heat removal capability was not degraded in all the examined monoblocks. ALMT W exhibited relatively smooth surface and higher resistance to cyclic heat loading. NSCM W exhibited severe surface modification and macro crack formation.
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S0022311520311272
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Silicon carbide ceramic matrix composites are being investigated as a new generation of fuel cladding materials due to its higher accident tolerance compared to Zircaloy . Characterization of the thermal conductivity of SiC constituents and their interfaces and interphases in SiC SiC composites is needed as inputs to models of cladding performance . We used time domain thermoreflectance to map the thermal conductivity with a spatial resolution of 2m . The SiC SiC composite is comprised of Hi Nicalon Type S fibers in a matrix made by chemical vapor infiltration . The interphase material is a pyrolytic carbon SiC multilayer . We report thermal conductivity maps of the SiC fiber and SiC matrix at temperatures of 25C 90C 164C and 250C . The fiber has a uniform and isotropic thermal conductivity of 22Wm
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High spatial resolution thermal conductivity mapping of SiC SiC composites. Thermal transport in the interphase material is dominated by interfaces. Thermal conductivity of SiC fiber is uniform isotropic and temperature independent. Thermal conductivity of the matrix in SiC SiC composites varies depending on location. Thermal conductivity of matrix has similar temperature dependence as impure crystal.
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S0022311520311296
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This article covers the investigation of tritium release and retention properties of beryllium pebbles with diameters of 0.5 and 1 mm after neutron irradiation at temperatures of 643 923 K and damage doses of 21 37 dpa corresponding to 3632 5925 appm helium and 367 644 appm tritium productions respectively . The thermos desorption spectra have a single main peak for both tritium and helium release . The peak temperatures at both used heating rates of 0.017 K s and 0.117 K s are in the range of 1052 1364 K for tritium and 1104 1336 K for helium release . The peak temperatures at a heating rate of 0.017 K s are always lower than at 0.117 K s. The tritium retention in both 0.5 and 1 mm beryllium pebbles considerably decreases by increasing irradiation temperature reaching of 1 18 at the highest temperature of 923 K regardless of the pebble diameter . Open channels are formed in the beryllium pebble microstructure at high irradiation temperatures . These microstructural features contribute to the enhanced release and low retention in beryllium pebbles under neutron irradiation .
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Tritium completely remains in beryllium pebbles irradiated at 643 and 723 K and most of it leaves the pebbles irradiated at 833 and 923 K. Formation of small gas bubbles and big pores occurs in beryllium under neutron irradiation up to high helium and tritium productions. Interconnected open channels which are formed in beryllium microstructure contributes to enhanced release and low retention of tritium.
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S0022311520311302
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A demonstration fusion reactor will require a huge amount of beryllium with approximately 490 tons . Since the total production of Be in the world for now is approximately 300 tons per year it is anticipated that the demand is dramatically increased as the early realization of the fusion reactor proceeds . The presence of many Be mines as well as information on each Be reserve has already been confirmed with surveys . Since a conventional Be refinement process is considerably complicated including a production process for an intermediate product Be
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A huge amount of beryllium Be with a weight of approximately 490 tons is necessary for DEMO. To provide a steady supply of Be for DEMO Be mine development is necessary including the installation of new refinement facilities. Beryllium ores were completely dissolved by base and acid solution treatment with microwave heating. A novel refinement process for creating Be metal from Be ores has been successfully established.
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S002231152031134X
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Radioactive iodine isotopes that are discharged into environment have been of significant concern due to its long term impact on public health . In this work a new bismuth based composite named
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was synthesized by electrospinning pre oxidation and carbonization. Carbonization could reduce Bi. to elemental Bi successfully. possessed high iodine adsorption capacity. Chemisorption by forming BiI. was the main capturing mechanism.
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S0022311520311375
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Evaluating the corrosion performances of wear resistant alloys is important for designing the molten salt wetted bearings and valves in molten salt reactors . In this study the corrosion behavior of wear resistant Tribaloy T 400 alloy in molten FLiNaK salt with and without the presence of UNS N10003 alloy were investigated through static immersion tests at 650C . After 400h corrosion T 400 alloy showed greater weight loss than UNS N10003 alloy and the presence of UNS N10003 alloy further increased the weight loss of T 400 alloy . Electron microscopic and salt chemistry analyses showed that Cr and Co were selectively dissolved from T 400 alloy matrix after corrosion resulting in a porous structure . On the other hand the Laves phase precipitates were hardly corroded but showed signs of carbide formation on the surface . In addition when tested with UNS N10003 alloy some of the Co dissolved from T 400 alloy transferred to the surface of UNS N10003 alloy hence promoted the corrosion of T 400 alloy . The results have indicated that even T 400 alloy has a relatively low Cr content among high temperature wear resistant hardfacing alloys its corrosion resistance is still inadequate in a typical molten salt reactor environment where UNS N10003 alloy and graphite are also present .
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The major elements that dissolved from T 400 into salts are Cr and Co. The matrix and Laves phase in T 400 alloy show difference corrosion behavior in molten fluoride salt at 650C. T 400 alloy shows severer corrosion than Alloy N in molten fluoride salt at 650C. To ensure the accuracy the experimental results a variety of material characterization experiments were combined.
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S0022311520311387
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Ageing of Cast Austenitic Stainless Steels was attributed to the decomposition of the ferrite by spinodal decomposition and precipitation of G phase particles . This leads to an increase in hardness and a decrease in Charpy impact energy . It is possible to restore the mechanical properties of these steels by annealing treatment above the Fe Cr miscibility gap in order to dissolve phase . In this work an annealing treatment for 2h at 550C followed by water quenching was applied to various Mo free and Mo bearing steels . This treatment allowed to restore almost completely the mechanical properties of Mo free steels and partly Mo bearing steels regardless of the initial ageing time . The mechanical property changes were attributed to the complete dissolution of spinodal decomposition and complete or partial dissolution of G phase particles . After annealing a re ageing kinetics was studied . The preexisting G phase particles have minor influence on the kinetic of spinodal decomposition until 2 400h at 400C .
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Effect of an annealing treatment at 550C on the microstructure and microhardness of the ferrite of Mo bearing and mo free steels. Kinetics of phase separation during re ageing after the annealing treatment in Mo bearing alloys. Thermal stability and evolution of G phase particles.
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S0022311520311399
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The solute segregation behavior at two types of carbideferrite interfaces was investigated by Atom Probe Tomography technique in a 16MND5 weld before and after ion irradiation . The two types of carbides are cementite and M
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A higher P segregation level at cementite ferrite interfaces than M. C carbideferrite interfaces. No influence of the intergranular carbides on solute segregation behavior at the vicinal GBs within the first tens of nm from carbides . A higher P segregation at the intersection region between carbide and GB. The RES mechanism of P at carbideferrite interfaces after ion irradiation.
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S0022311520311430
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Temperature monitoring of reactor experiments is an important quality requirement . High purity silicon carbide can be used to provide such data through post irradiation material analysis . This method stems from radiation defect concentrations dependence on irradiation temperature . Irradiation temperature can be determined by measuring irradiation induced property changes for example lattice spacing distribution dimensions electrical resistivity etc.after isochronal annealing . Such methods are time consuming since multiple steps must be performed in a serial manner . We investigated the possibility of using an alternative method that does not require multiple heat treatments . Instead peak irradiation temperature is determined by a calibration curve comparing pre and post irradiation sample dimensions . The experimental results demonstrate the feasibility of this approach in the irradiation conditions described below . This approach can also be used to measuring changes in other properties mentioned above .
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Irradiation capsules were designed and fabricated for simultaneous irradiation of SiC samples at 255 310 and 410C 528 583 and 683K . Irradiation was performed in a driver fuel element of the BR2 reactor in Mol. Radiation induced dilatation of SiC samples was measured after irradiation. A demarcation energy approach was used to interpret the results. It is proposed that peak irradiation temperature be determined by a calibration curve comparing pre and post irradiation sample dimensions.
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S0022369718329172
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In this work surface metallization of cotton fabrics was performed by electroless plating using a shorter route than is conventional . The fabric surface was activated by deposition of silver and copper nanoparticles and then a thin layer of copper was coated using electroless plating . The performance of coated fabrics was compared in terms of electrical conductivity electromagnetic interference shielding Joule heating and antibacterial properties with another sample coated with conventional electroless plating . The orthogonal array testing strategy was adopted to optimize the various factors of the electroless plating bath . The samples prepared by electroless plating of copper showed greater performance for the fabric first deposited with silver particles than those first deposited with copper particles or conventionally treated . Samples of copper electroplating over silver had surface resistivity of 20 EMI shielding of 75.53dB and Joule heating of 83.1C . Moreover samples with modified electroless plating showed better attachment of the metal layer and therefore longer durability .
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Performed modified electroless plating of copper in shorter route. Prior deposition of silver and copper nanoparticles resulted in uniform electroless plating. Electroless plating of fabrics deposited with silver particles showed greater performance. Surface resistivity of 20 EMI shielding of 75.53dB and joule heating of 83.1C achieved. Modified electroless plating provided longer durability than conventional electroless plating.
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S0022369718329950
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Fabrication of hybrid nanostructured catalysts has emerged as a current trend for efficient treatment of wastewater . In this work a simple wet chemical approach was used for the synthesis of CuO Cu
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CuO Cu. O hybrid nanowires were synthesized by a facile wet chemical route. SEM TEM and high resolution TEM studies revealed the formation of CuO Cu. O hybrid nanowires. CuO Cu. O hybrid nanowires exhibited highly enhanced catalytic efficiency for reduction of 4 nitrophenol to 4 aminophenol.
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S002236971833292X
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Silicon clathrates are Si cage based structures capable of hosting other atoms such as sodium in their Si polyhedron cages . Electron spin resonance can provide information on the electronic structure of localized or delocalized electrons in cage like type II silicon clathrates of the form Na
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Isolated Na atoms in Na intercalated type II silicon clathrates are identified as donors by electron spin resonance. A Na atom in a Si. polyhedron is displaced along the 111 direction by the Jahn Teller effect. Low temperature electric conductivity is caused by electrons moving in Na clusters or hopping between Na clusters.
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S0022369719301544
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In this study we investigated the electronic structure of halide perovskite titania interfaces using first principle methods . Based on the different possible terminations of methylammonium PbI
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Interlayer composition and band alignment linked in perovskite titania interfaces. PbI terminated perovskite titania interface more stable than MAI titania. PbI titania interface level alignment better than that for MAI titania. Proton induced downshift of conduction band for TiO. affects band alignment.
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S002236971930160X
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Single crystals of Oxalic acid dihydrate Potassium oxalate hydrate Potassium hydrogen oxalate oxalic acid dihydrate were grown using solvent evaporation technique . Unit cell parameters of the crystals were studied using single crystal XRD and the crystal parameters were found to match with the reported values . Structural properties were studied using powder XRD analysis . Optical absorption studies were carried out to determine the light absorption by the crystal and the optical bandgap was also calculated using Tauc s relation . Emission and thermal properties of the OAD KOH and KHOOD crystals were studied using photoluminescence spectroscopy and TGA DTA measurements respectively and explained in detail . Electrical studies were also carried out to find the resistivity of the material . The hardness of the synthesized crystal was also explored and the parameters such as stiffness constant yield strength fracture toughness and brittleness were evaluated and compared .
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Comparative studies on the OAD KOH and KHOOD single crystals are reported. The OAD KOH belongs to Monoclinic and KHOOD belongs to triclinic crystal system. OAD KOH and KHOOD crystal bandgaps are 4.06 4.28 and 4.10 respectively. The Mayer s number for OAD KOH and KHOOD are 1.78 2.32 and 1.54 respectively. Thermal stability is more for KOH single crystal.
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S0022369719301921
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Although tin sulfide is a potential thermoelectric material it has not been applied commercially because of its low intrinsic electrical conductivity . Doping is a possible method to improve the thermoelectric properties by promoting its electron and phonon transport characters . In this work we constructed calculation models for SnS and Sn
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A reliable calculation method for thermoelectric properties of doped SnS was proposed. Improved thermoelectric properties of SnS by Bi doping were shown. Optimum Bi content was determined theoretically which is difficult to do experimentally. Importance of the electron thermal conductivity for the. value was shown.
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S0022369719302550
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Density functional theory in conjunction with ab initio atomistic thermodynamics were used to investigate the stability of the low index cuprous chloride surfaces and predict the morphology of CuCl nanocrystals under high pressures of chlorine . The rocksalt orientation of the lattice was adopted to resemble a CuCl crystal under high pressure . Under Cl lean conditions the defective CuCl Cl structure was found to be the most stable configuration among all surfaces investigated . Under Cl rich conditions a flawless CuCl surface with Cl termination becomes the most stable configuration . It was shown that in a diluted chlorine environment the CuCl in zinc blende structures are more stable than the CuCl in rocksalt configurations while under a chlorine rich environment the CuCl in rocksalt structures are more stable than the CuCl in zinc blende configurations . At low pressure of chlorine it was found that the facets are the most dominant to the Wulff construction giving the crystal a coffin shape . As the pressure of chlorine increases however the involvement of the facet increases giving the crystal a semi dodeca hedron shape . At high pressure of chlorine the major contributors to the Wulff construction were found to be the facets resulting in the formation of dodeca hedron nanocrystals .
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CuCl in Rocksalt structure has been adopted to resemble a crystal under high pressure. Rocksalt structures are more stable than zinc blende configurations at high pressures. At high pressure of chlorine the nanoparticle has a dodeca hedron shape.
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S0022369719304433
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X ray absorption fine structure spectroscopy was used to address both the local atomic structure and the local electronic structure around Zn Co and S in Co doped ZnS thin films . X ray absorption near edge spectroscopy revealed changes in the strong pre edge feature of the S K edge spectra that depend on the Co concentration and are related to atomic bound state transitions through hybridization between 3
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Co substitutes for Zn generating lattice distortions. The shortening of the CoS distance results in a decrease in the lattice parameter. The main defects in the structure are Co substitution at Zn sites and S vacancies. Co concentration is coupled with changes in the unoccupied local electronic states.
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S0022369719304652
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On the semi insulating 4HSiC surface hydrogenated multilayers graphene were epitaxially prepared by the method of Joule heating decomposition in the hydrogen atmosphere . The structural and chemical characteristics of multilayers graphene have been elaborately analyzed by the X ray photoelectron and Raman spectroscopies showing the level of hydrogenation being promoted with the increase of hydrogen pressure . Then diodes with MLG 4HSiC contact were fabricated and studied proving that the Schottky barrier height of MLG 4HSiC junction was enhanced by the hydrogenation . By studying the typical current voltage characteristics the SBH was observed to be heightened from 0.84eV to 1.0eV along with the hydrogen pressure increasing from 10
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A Joule heating decompostion method has been employed. Bandgap of epitaxial multilayers graphene could be opened and modulated by different level of hydrogenation. Schottky barrier height as high as a 1.0eV have been achieved at the 10. mbar hydrogen pressure.
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S0022369719305104
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In this study we numerically determined the intra band transition lifetime of carriers as well as the linear nonlinear and total absorption coefficients fro lens shaped core shell quantum dot structures . Our computations considered the combined effects of the wetting layer pressure applied transverse electric field temperature and core shell sizes . By using suitable choices for these parameters we found that a red or blue shift in the energy of the absorption spectrum could be achieved . In addition the largest absorption coefficient was obtained when an intense transverse electric field was applied along the diagonal of the cross section of the structure considered . Hence the magnitude of the absorption coefficient increased by 50 . Moreover our results showed that the transition lifetime of the carriers decreased as the temperature increased whereas it increased as the pressure increased . Comparative analysis of a semi spherical core shell quantum dot system showed that the transition lifetime was shorter than that of the lens shaped core shell quantum dot structure which was 255ns .
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Optimization of lens shaped InAs GaAs core shell quantum dot structure. Investigation of linear nonlinear and total absorption coefficients. Exploration of the transition lifetime. Effects of wetting layer pressure temperature and transverse electric field. Comprehensive study conducted within framework of finite difference method.
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S0022369719306213
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The properties of nickelcobalt alloys depend greatly on their composition . In this study we investigated the crystal structure and mechanical properties of nickelcobalt alloys with different compositions based on first principles calculations . The formation enthalpy
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Structure of NiCo alloys changes from fcc to hcp as cobalt content increases. fcc and hcp phases coexist at cobalt contents of 5080at. . Formation enthalpy same for fcc phase and hcp phase at cobalt content of 65.5at. . Stiffness hardness and compression shear resistance enhanced by high Co content. Improved mechanical properties due to enhanced covalent bonds between NiCo and CoCo.
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S002236971930650X
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Using density functional theory we have investigated the adsorption characteristics of several explosive compounds on the concave and convex surfaces of a variety of buckybowl materials corannulene sumanene monoindenocorannulene
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Curvature plays a vital role in the adsorption of explosives. SUMA exhibits the enhanced adsorption of explosive compounds. Electrostatic interactions are predominant between SUMA and the explosive compounds studied. Concave buckybowl materials are sensitive towards all the explosive compounds studied.
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S0022369719306638
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In the present work a novel cupric oxide decorated on cyclodextrin nanocomposite was synthesized by sonochemical method . The CuO CD nanocomposites were characterized by UVvis Raman FT IR FE SEM mapping analysis XRD techniques . Fascinatingly the CuO CD nanocomposite Nafion solubilized modified glassy carbon electrode has exhibited a superior electrocatalytic activity towards the
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Cupric oxide decorated cyclodextrin nanocomposite was synthesized using sonochemical method. Cupric oxide decorated cyclodextrin nanocomposite shows enhanced electrocatalytic detection of. tyrosine. It is owing to better electron transfer efficiency and high surface area of the nanocomposite modified electrode. Amperometric technique is adopted to identify low detection of. tyrosine in the presence of real samples.
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S0022369719306730
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In this work the effective field theory is used to investigate the electrocaloric effect of a ferroelectric nanocube with core shell morphology described by the transverse Ising model . We have elucidated the influences of the external electric field
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The electrocaloric effect of a ferroelectric nanocube with core shell morphology is studied. The influence of the interfacial coupling on the thermal properties of a nanocube has been examined detailed. The electrocaloric effect depends strongly on the applied electric field.
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S0022369719306869
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Direct and converse piezoelectric effects have been observed in human tooth enamel and dentin . In this study organic material was removed from dentin and enamel using a chlorinated solution to measure the sole contribution of the inorganic phase . In the direct mode piezoelectricity is observed when a force applied to the sample produces a voltage . A variable load was applied to the samples with a Shimadzu universal testing machine . In the converse mode mechanical deformation of the sample occurs under an electric field which was detected using an atomic force microscope in the piezoelectric mode . For comparison measurements were also performed on samples where organic and inorganic phases were present . Although a decrease in of the electromechanical response of the organic free sample was observed the results indicate that the inorganic phase contributes to the piezoelectric property in dentin and in a lesser extent in enamel . This suggests that tooth dentin and enamel apatite nanocrystals present piezoelectric non centrosymmetric P6
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Piezoelectricity of tooth hydroxyapatite in dentin and enamel was measured. Piezoelectricity of hydroxyapatite in dentin is larger than that in enamel. Piezoelectricity decreases in tooth samples when the organic material is removed. Centro and non centro symmetric spatial groups coexist in the tooth structure. Piezoelectricity could stimulate healing growth of teeth as it does in bone.
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S002236971930705X
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The 2 amino 5 bromopyridinium trifluoroacetate crystal has been successfully grown by solvent slow evaporation technique . The grown crystal is found to non centrosymmetric space group Pna2
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The research discloses the discovery of novel 2 amino 5 bromopyridinium trifluoroacetate 2A5BPTFA as an efficient organic material for NLO applications. 2A5BPTFA exhibits blue emission confirmed by Photoluminescence studies which proves to be an eligible candidate of fabrication of blue organic LED. This is exhibits second harmonic generation. The relative NLO efficiency of 2A5BPTFA has 2.44 times larger than that of KDP. The study report 2A5BPTFA exhibits self focusing nature and the optical limiting threshold values confirm the suitability in optoelectronic applications.
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S0022369719307358
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The materials referred to in this work are two cyano oligo phenylene vinylenes soluble in chloroform possessing donor and acceptor groups with a completely extended electron system on the whole chain . For a better description of the correlation structure properties of these new materials we proceeded via spectroscopic analyses and experiment techniques such as thermogravimetric analysis infrared spectroscopy optical absorption and photoluminescence . This experimental study is consolidated by a theoretical study based on the Density Functional Theory allowing the determination of their structural and optoelectronic properties conformation gap E
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A combined Experimental and computational study based on Density Functional Theory DFT study of two new PPV derivatives DOMCN and DBrCN . Electronic structure molecular orbital excited state energies. Noncovalent Functionalization of two Single walled carbon nanotubes SWCNT SWCNT 5 5 and SWCNT 6 4 with the DOMCN compound as active layer. Van der Waals interactions in a stacking coupling of the SWCNT and the organic matrix. A preliminary results on the diagrams energy and injection barriers in the organic light emitting diodes OLEDs .
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S0022369719307462
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Relaxation analysis has been carried out on lithium graphite intercalation compound focusing on the variation of stage structure and graphene interlayer distances . X ray diffraction coupled with the one dimensional Rietveld analysis revealed that after the termination of electrochemical lithium insertion excessively formed stage I partly transforms into stage II during the relaxation process . In addition the periodic stacking of defective lithium layers forming stage II orders the lithium occupation at the relaxation which is more apparently observed for faster charged sample . Even after the lithium extraction gradual stage changes from I to II accompanied by the ordering of lithium occupation in stage II have been observed at the relaxation process . Lithium ion is rather uniformly intercalated or deintercalated in the graphene interlayers while Li GIC turned into ordered stage structure to achieve the stable state at the relaxation time .
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After Li insertion into graphite stage I partly changes into I and II at relaxation. Lithium occupied interlayers in stage II orders at relaxation. Even for Li extraction stage change from I to II was detected at the relaxation.
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S0022369719307541
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The binder free technology is used to produce flexible self standing cathodes for secondary Li ion batteries containing commercial materials lithium manganese oxide and multiwall carbon nanotubes . The fragmentation of commercial LMO by short time ball milling with low energy intensities allows one to reduce the particle size from tens of microns to the micron and submicron level while maintaining its spinel crystal structure . The electrode exhibits high electrical conductivity 46Sm
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Binder free flexible LMO cathode has been obtained using simple technology and commercial materials LMO and CNT. Short time ball milling increases specific surface area of LMO particles while maintaining it spinel structure. Cathode material in aqueous electrolyte revealed a specific discharge capacity of 110 mAh g. after 1. cycle at 0.6 C.
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S0022369719307668
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A mixture of boric acid combined with trivalent samarium doped sodium borate was fired in air at 450C . The addition of water to the hot residue resulted in the generation of a product in which the incorporated samarium has been reduced from the trivalent form to the divalent state as identified by emission spectroscopy . This product has been identified as a synthetic form of the mineral sborgite . The divalent samarium emission appears to result from the samarium ion occupying a boron site in the material .
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Sm. is formed in a sodium borate system fired at 450C. The Sm. environment seems consistent in a variety of sample compositions. Such a method could reduce other lanthanides such as europium ytterbium or thulium.
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S0022369719307681
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Using three organic materials in the cascade configuration of organic photovoltaic cells broadens the absorption range of visible light resulting in an increase in the short circuit current density . Herein we report for the first time the use of three organic molecules pentacene boron subphthalocyanine chloride and fullerene C
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The open circuit voltage in ternary OPVCs is limited by the outmost band levels. The efficiency of ternary OPVCs pentacene SubPc C. surpass that of their corresponding binary cells. The efficiency of OPVCs containing pentacene is limited by the small induced Voc value. The use of MoO. as the bottom layer improves the pentacene film quality.
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S0022369719307796
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In recent years due to high usage of fuel cells the development of novel catalysts to oxygen reduction reaction with high efficiency is a fundamental principle . In current study in acidic environment the performance of Al zigzag SiNT Al armchair SiNT and Al chiral SiNT to ORR were studied by theoretical models . Possible pathways for ORR on Al zigzag SiNT Al armchair SiNT and Al chiral SiNT via Eley Rideal and Langmuir Hinshelwood were examined . The optimal mechanism to ORR on Al zigzag SiNT Al armchair SiNT and Al chiral SiNT from thermodynamic view point was proposed . The overpotential values on Al zigzag SiNT Al armchair SiNT and Al chiral SiNT surfaces are 0.34 0.36 and 0.39V respectively . The calculated overpotential are lower than overpotential on platinum based catalysts . Finally the Al zigzag SiNT can be proposed as catalysts to ORR with high performance .
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Oxygen reduction reaction on Al zigzag SiNT 9 0 and Al chiral SiNT 9 3 was investigated. Oxygen reduction reaction was done via ER and LH mechanisms. Optimal pathway to oxygen reduction reaction on Al zigzag SiNT 9 0 was recognized. The Al zigzag SiNT 9 0 has higher potential than platinum based catalysts. Al zigzag SiNT 9 0 as novel catalysts to oxygen reduction reaction was proposed.
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S0022369719308194
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Nanoporous gold structure gains several unique physical and chemical properties from its nanoscale foam structure composed of ligaments and connected pores . The high specific surface area and interconnected pores make its structure ideal for gas catalysis . Catalytic activity arises in part from the high number density of surface steps and kinks at points of high curvature in the nanoporous structure . However the structure also makes the material macroscopically brittle and unreliable for many applications due to poor mechanical stability . The ligament diameter which regulates both desirable chemical properties and mechanical instability can be tuned to over three orders of magnitude but few morphology features can be adjusted independently of this . Here we fabricate nanoporous gold with an average ligament diameter of around 10nm while varying synthesis parameters and quantify the resulting morphology in order to evaluate the effect of processing on the resulting nanoscale foam structure .
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The ligament diameter distribution width can be tailored by controlling the coarsening rate. The ligament curvature can be tailored through mechanical agitation during dealloying. Grain boundaries interacted strongly with crack propagation during. tensile straining. Ligaments up to 200nm from the crack tip experienced small plastic and elastic deformation.
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S0022369719308558
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In recent years perovskite solar cells are performing remarkably with efficiency more than 20 . Performance can further be improved by controlling charge transfer and recombination at electron transport material absorber and absorber hole transport material interfaces which ultimately define conduction band offset and valence band offset . Therefore it is worthwhile to investigate optimum band offset to get efficient PSCs . Spiro MeOTAD is organic HTM commonly used in PSCs while CuI CuSCN and Cu
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Comparative study of device engineering of perovskite solar cell with different organic and inorganic HTMs. Effect of CBO VBO and N. of interfaces on the performance of the devices is investigated. The PSC with CuI as HTM exhibits best PCE of 22.69 . This study shows useful inorganic HTMs alternate to traditional organic HTM. Performance of the PSCs strongly depends on the defect density and band offsets.
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S0022369719309047
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This paper introduces two novel structures for silicon on insulator metal oxide semiconductor field effect transistor with nanoscale dimension and superior electrical performance . One structure only incorporates retrograde halo dopants in the source side and uniform halo dopants in the drain side . The other device comprises dual material in the gate contact along with RHD in the source side and uniform halo dopants in the drain side . Incorporation of retrograde dopants in the source side and uniform doping in the drain side of RHD and DM RHD lead to improvements in the leakage current sub threshold slope and short channel effects . Hot carrier injection to the gate channel length modulation and drain induced barrier lowering are significantly improved with respect to the conventional SOI MOSFET . The auxiliary gate along with the main gate in the DM RHD structure improves off current control in the channel compared with RHD and CSOI counterparts . Because the proposed devices show these positive features they can be utilized to satisfy International Technology Roadmap for Semiconductors requirements for next generation devices .
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A novel architecture for silicon on insulator SOI transistor is proposed. Dual material in the gate and halo doping improves electrical characteristics. Simulation study produces transfer characteristics and transconductance. Important transistor characteristics are compared for three structures. The proposed structure is more persistent against short channel effects.
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S0022369719309126
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In this study based on density functional theory calculations we investigated the stable configurations electronic structures and magnetic properties of metal and non metal atom modified graphene substrates . The single atom metal embedded divacancy graphene exhibited high stability and the 555 777 graphene Fe system had a larger magnetic moment than the Ni doped system . The adsorption of NO on 555 777 graphene Fe was more stable than that of the HCN NH
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The 555 777 graphene Fe system had larger magnetic moment than other systems. NO molecule adsorbed on 555 777 graphene M sheets was most stable. Gas molecules more stable on 3Si graphene M than 555 777 graphene M. Gas adsorption regulated electronic and magnetic properties of 3NM graphene M.
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S0022369719309680
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The Langmuir Blodgett alternate layer fabrication technique provides one of the most effective methods to fabricate organic thin films in the nanoscale . The structure of these thin films could be controlled at the molecular scale by spreading a monolayer on an air water interface followed by sequential transferring of this layer onto a selected solid substrate . These films can be utilized within optical electrical and biological applications in many different fields . Within this paper two calixarenes containing either carboxylic acid or amino substituents were utilised to prepare multilayer LB films and to study the electrical characteristic of these films using IV and C f measurements . The resultant calixacid amine multilayers demonstrated a highly non linear IV behaviour which obeys a Schottky conduction mechanism .
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This study is based on the Langmuir Blodgett LB thin film fabrication and electrical properties of novel calix 4 arene acid and amine molecules. Monolayer behaviour of these materials at the water surface is investigated and a well organized and stable monolayer with a 22.5mNm. surface pressure value is found for LB film deposition. Calix 4 acid molecule was deposited alternately with calix 4 amine to fabricate a multilayer LB film structure with a high transfer ratio 0.90 onto aluminium coated glass substrate. Calix n arene Langmuir Blodgett film structure is fabricated to study the electrical properties using I V C f measurements..
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S0022369719309953
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Functionalized MXenes exhibit versatile potential applications in supercapacitors hydrogen storage and sensor materials . In this paper we have systematically explored the pressure induced band modulation work function and optical properties of a Sc
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Sc. CF. monolayer undergoes a semiconductor to metal transition under 9GPa. The left hand shift of Sc d of CBM and the right hand shift of Sc d and C p of VBM result in the metallization at 9GPa. The work function can be effectively engineered using pressure.
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S0022369719310509
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Density functional theory calculations including the effect of van der Waals forces have been performed to study the adsorption of isocyanic on the defective and perfect Rh surfaces . We have considered Rh adatom on Rh surface as a model of defective Rh surface . Our calculations show that on the perfect surface the HNCO prefers to adsorb on the bridge site with or without the inclusion of vdW correction . However the inclusion of vdW forces results in the reduction of adsorption energy relative to values obtained from pure DFT . Regarding the defective surface in particular the Rh adatom results in greater stability of the adsorbed HNCO when compared to HNCO adsorbed on a perfect surface . Also the interaction between the HNCO and the surface has been analyzed in terms of projected density of states . It is observed that huge hybridization occurs between the
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HNCO has been studied on the flat and defective Rh 001 surfaces using pure DFT PBE and DFT vdW revPBE calculations. HNCO prefers to adsorb on the bridge site with or without the inclusion of vdW correction. Inclusion of van der Walls forces results in the reduction of adsorption energy relative to values obtained from pure DFT. The Rh adatom results in greater stability of the adsorbed HNCO when compared to HNCO adsorbed on a perfect surface. The analysis of the PDOS has revealed a huge hybridization between N 2. orbital and Rh 4. band.
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S0022369719311345
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The structural changes and thermal decomposition of kaolinite intercalation compounds during heating process limit their application in polymers which need to be heated during the preparation process . In this study homologous compounds namely hexylamine and octadecylamine were used to intercalate Kaol to explore the effect of molecular chain length on the structural stability and thermal decomposition of intercalated compounds . After the intercalation by HEA and OCA the expansion only occurred along the C axis and the basal spacing increased to 28.7 and 57.3 respectively . The morphology of Kaol changed remarkably and all appeared curly . Compared with Kaol HEA intercalation compounds the Kaol OCA intercalation compounds had better curling effect due to their different molecular chain length . The thermal decomposition process of Kaol alkylamine intercalation compounds can be divided into two distinct stages . The molecules that adhered to the surface of the nanoscrolls and existed in the lumen of nanoscrolls began to deintercalate in the first step and the other molecules that intercalated Kaol layers began to decompose in the second step . Thus Kaol can be used as a potential carrier material a carrier of sustained release drug or a carrier material for the catalyst . The reaction is regulated by controlling the temperature of the reaction .
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The structural models of the kaolinite intercalation complexes were proposed. The effect of molecular chain length on the structural stability of intercalated composites was investigated. The different chain length caused a significant difference in thermal stability of the Kaol intercalation compounds.
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S0022369719311497
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In our quest for unlocking the growth mechanism of polymer stabilized metal nanostructures we stumbled upon the solventless templateless redox reaction between the monomer N vinyl pyrrolidone and tetrachloroauric acid . This simple reaction results in the formation of oligomer bridged ultra small Au nanoparticles through an auto catalyzed cluster aggregative nucleation process even under ambient conditions in the absence of any other external energy resources . Such intriguing self assembled nanostructures were beautifully illustrated through the TEM images that are in strong correlation with the observed multiple optical absorption signatures . But the sharp intense peak at around 633nm was quantified by quasi static dipole model theoretical calculations as the predominantly coupled dimer peak signifying the highly localized formation of small cross linked aggregates . Augmenting the same the real time
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NVP monomer utilized as both reducing and capping agent. Solventless templateless redox reduction leads to oligomer coupled ultrasmall Au nanoparticles. Coupled dimer peak simulated by dipole model. Nanostructure property structural functional relationship explained.
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S0022369719311667
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Glasses doped with rare earth ions have attracted considerable interest because of their potential applications in photonic devices such as phosphors optical amplifiers lasers and memory . The design and preparation of host glasses for doping RE ions are very important for achieving the desired performance in different devices . In this study we successfully prepared nano sized SnO
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Fabrication of nano sized SnO. crystal precipitated glasses activated with Eu. ions. Glasses exhibited strong fluorescence intensities. Eu. ions successfully co doped in precipitated SnO. nanocrystals. Optical energy absorbed in SnO. crystals transferred to co doped Eu. ions. Emission yield was 75 even with a low Eu. content of 0.5wt .
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S0022369719311795
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In this work we consider an open single level molecular junction with electrons coupled to a single frequency phonon mode in which the phonons are also coupled to another heat bath . By applying a temperature gradient between the electrical leads and investigating thermocurrent in non linear regime it is shown that the environment can excite phonons which may result in either suppression or very significant enhancement of thermocurrent depending on the onsite energy . Similarly in the linear regime the effects of environment are seen in the Seebeck coefficient .
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Thermo current and thermo power are calculated for molecular junctions. Environment can change thermo electric properties by exciting phonons. Thermo current is enhanced noticeably by environment at some regimes. The Seebeck coefficient approaches a zigzag behavior by increasing the temperature of environment.
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S0022369719311953
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Metal oxide photocatalysts have high chemical stability in aqueous solutions but their photocatalytic activity is usually restricted by poor electronhole separation . Although impurity doping has been demonstrated to be an effective way to tune photocatalytic properties the mechanisms of enhanced photocatalytic activity remain ambiguous . Here we show that appropriately incorporated impurities can markedly improve the spatial carrier separation and photocatalytic activity . This concept is demonstrated by experimental and density functional theory studies on the effects of fluorine and nitrogen dopants on photocatalytic H
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Photocatalytic activity of FN codoped ZrO. was studied by Experiments and DFT. FN codoping enhances the spatiotemporal separation of carriers. FN codoping reduces overlap of electrons and holes and carrier recombination. A PBE U method in accord with HSE functional was proposed to correct bandgap underestimation.
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S002236971931251X
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In the present study we performed density functional theory calculations in order to study the structure and stability of small Ni clusters embedded in graphene multivacancy systems . The Bader charges band structure total density of states partial density of states and spin density magnetization were obtained to understand the effects of the cluster size on the electronic and magnetic properties and thus to determine their potential applications in spintronic devices . Ni cluster adsorption modified graphene multivacancy substrate behavior and conversion from a conductor to a semiconductor could be achieved when the cluster size was changed . A linear dispersion relationship around the reciprocal point K was conserved for most of the systems with the inclusion of a band gap between the Dirac cones which is important for obtaining semiconductors with massless fermions . Comparisons with Ni clusters adsorbed in pristine graphene showed that combining vacancy defects with Ni allows higher band gaps to be obtained . We also analyzed the interactions between Ni clusters and vacancy defects based on the PDOS results . Ni clusters with different sizes could generate ferromagnetic and ferrimagnetic couplings with graphene that exhibited three four and six D
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Ni. structures embedded in multivacancy graphene studied using DFT. Conductor to semiconductor conversion observed as Ni cluster size varied. Multivacancy defects increased charge transfer from Ni clusters to graphene. Ferromagnetic ferrimagnetic and nonmagnetic behavior observed. Absorbed Ni. and Ni. clusters could be applied as dilute magnetic semiconductors.
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S0022369719313113
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Ab initio calculations based on density functional theory are used to study the structural energetic electronic and magnetic properties of lithium aluminate LiAl
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The properties of lithium aluminate LiAl. spinel doped with Fe and Cr are studied. Exchange and correlation effects are described via the GGA PBEsol and mBJ potential. A Bader analysis shows that the defect charge is 3 for both Fe and Cr. For replacement of Al by Fe Fe. has a valence electron configuration of 4s. 3d. 8c and 12d sites . For replacement of Al by Cr Cr. has a valence electron configuration of 4s. 3d. 8c and 12d sites .
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S0022369719313150
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Semiconductors encompassing a broad range of novel electronic magnetic and optical properties have attracted substantial research interest over the past decade promising the development of next generation multifunctional devices . Recently we have observed strong visible optical absorption in AlP after Mn doping . Here the magnetic interaction and optical absorption in Al
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Mn doped AlP energetically favors a ferromagnetic state with short range exchange coupling interaction. The Curie temperature can be continuous enhanced even above 220K by in plane biaxial strain. A strong optical absorption in the visible range as well as its intensity are almost unperturbed by the applied strain. Our findings open up novel strategies for constructing multifunctional diluted magnetic semiconductor materials.
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S0022369719313253
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A novel model of multi dual phase lag generalized magneto thermoelasticity is presented . It is applied to treat a thermal shock for a fiber reinforced anisotropic half space . The medium is subjected to a primary magnetic field as well as a thermal shock . The normal mode technique is applied to solve the coupled differential equations and the physical fields are derived . Different mechanical and thermal loads are applied on the surface of the medium . Validation examples are presented and results due to different theories are compared . The effects of the magnetic field parameter and different thermoelasticity theories on all physical fields are investigated .
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A novel model of multi dual phase lag generalized magneto thermoelasticity is presented. The medium is subjected to a primary magnetic field as well as a thermal shock. The normal mode technique is applied to solve the coupled differential equations and the physical fields are derived. Validation examples are presented and results due to different theories are compared. The effects of magnetic field parameter and different thermoelasticity theories on all physical fields are investigated.
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S0022369719313617
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This work presents for the first time the properties of the liquid phase of silicon carbide using ab initio molecular dynamics simulations based on density functional theory . Our DFT scheme employs a plane wave basis to expand the atomic orbitals pseudopotentials built with the projector augmented wave method and the local density approximation to describe the exchangecorrelation interactions . With this approach we we determine a melting temperature of the zinc blend phase of 2678.54
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The structural thermodynamic dynamic properties of silicon carbide are predicted with ab initio methods. Diffusion coefficients and melting temperatures are calculated as a function of pressure. Comparison with experimental shows the accuracy once more of density functional theory.
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S002236971931385X
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Two dimensional nanocrystals with semiconducting electronic properties are emerging as promising materials for electronic devices . Here we present the density functional theory calculations of structural stability Raman spectra and electronic properties of monolayer bilayer and trilayer antimony . The cohesive energy and phonon band dispersion results revealed that free standing Sb systems are stable materials . Calculated Raman spectra showed distinct active modes thus facilitating the characterisation of multilayered structures in different stacking arrangements . It was found that high frequency in plane E
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Cohesive energy and phonon band dispersion results revealed that free standing antimony Sb systems are stable materials. The results show that AB and ABC stacked Sb are energetically more favourable than AA and AAA stacking order respectively. Distinct Raman frequencies were seen for different stacking layers which is quite useful to identify layer thickness.
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S0022369719313861
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The uptake of pollutant gases from the environment is an important topic in nanomaterial science . Although this issue has been extensively studied from all aspects there is still a need for efficient adsorbent substrates . As carbon based materials are reliable for removal of gas molecules we studied the capacity of the recently predicted monolayer of
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Semiconductor monolayer. CO becomes metallic under adsorption of a Ni adatom. S dissociation on Ni doped Pmma CO is favored.
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S0022369719313964
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One of the key challenges in developing lithium ion batteries is the super long cycles . Two dimensional materials with a layered crystal structure disclose many advantages and attract more interests in this field . Here we report a novel method through which the electrochemically exfoliated graphene is employed to construct an anode for ultra long cycle Li ion batteries . The high quality EG was directly sprayed onto the copper foil as a binder free material resulting in high conductivity high volume capacity and bridging properties . The battery has exhibited a high capacity of 356mAhg
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A novel method is electrochemically exfoliated graphene EG . The high quality EG was directly sprayed onto the copper foil as anode. The battery has exhibited a high capacity and capacity retention over 6500 cycles.
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S002236971931409X
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Structural and elastic properties of the two known hydrated phases of calcium carbonate were investigated . A comparative study was conducted where computer atomistic simulations based on standard density functional theory and dispersion corrected density functional theory were performed . Properties such as the elastic constants the bulk modulus the Young modulus the shear modulus the Poisson ratio the velocities of acoustic waves and the Debye temperature were evaluated for the first time at the DFT level of theory . As most of the properties investigated have not been measured experimentally yet the DFT PBE and DFT D2 values provide limits that allow bracketing of the unknown experimental values . The evolution with pressure of the structural and elastic properties of ikaite and monohydrocalcite was investigated in the range from 0 to 5GPa . In monohydrocalcite a brittle ductile transition is predicted to occur between 1.3 and 2.2GPa .
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Structural and elastic properties of ikaite and monohydrocalcite were investigated. The elastic and derived properties were determined for the first time at the density functional theory DFT level of theory. A comparative study based on standard DFT and DFT D2 was conducted. The calculated DFT PBE and DFT D2 values provide limits which allow bracketing of the unknown experimental values. A ductile fragile transition is predicted to occur between 1.3 and 2.2GPa in monohydrocalcite.
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S0022369719314301
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We report the facile in situ doping of soluble conducting polypyrrole with cadmium sulfide quantum dots aimed at tuning the mid infrared photoconductivity of PPy films with a planer structure . The doping was done during chemical polymerization of PPy with different mass ratios of the as synthesized CdS QDs . The PPy CdS QDs films were fabricated by electrospray coating between gold interdigitated electrodes . The incident light in the MIR region 7.62mW cm
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Doping of soluble polypyrrole PPy with CdS quantum dots QDs during chemical polymerization. Electrospray coating of PPy doped with CdS QDs as photosensitive film with a planer structure. QDs doping enhanced the mid infrared photoconductivity of PPy film in the optimum conditions. Good photosensitivity good repeatability and independent response in the mid infrared region were achieved.
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S0022369719314490
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The development of new and simple surface enhanced substrates is primarily motivated by the ability to design and investigate the plasmonic structures to achieve the optimal performance in enhanced spectroscopy . In this work we numerically design the plasmonic substrates by embedding a nanorod dimer antenna into a nanoring resonator . The single layer composite substrate reveals a double resonance response with a broad spectrum electric field enchantment due to the plasmon hybridization of nanorod dimer and nanoring . The sandwiched substrate shows a complicated optical spectrum with multiple plasmon resonances which can be attributed to the interaction of intralayer and interlayer plasmons . It is also worth mentioning that the electric field hot spots keep unmodified and concentrate at the middle gap of nanorod dimers in composite substrates at different excitation frequencies . The enhanced plasmonic substrate with consistent hot spots at different excitation frequencies can be used in surface enhanced Raman spectroscopy and nonlinear optics .
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The dual band plasmon resonances with wide SERS activity can be realized in hybridized nanorod dimer plasmon substrate. The multi band plasmon enhanced substrates with unchanged hot spots can be realized in hybridized nanorod dimer. The hot spots in designed plasmon enhanced substrates remain unchanged at different excited wavelengths.
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S0022369719314532
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A novel one pot synthesis of polypyrrole reduced graphene oxide nanocomposites with the aim of assessing their potential as a cold cathode material is reported . r GO was prepared by a modified Hummers and Offeman method . The nanocomposites were characterized by transmission electron microscopy field emission scanning electron microscopy X ray diffraction Fourier transform infrared spectroscopy and Raman spectroscopy . The isothermal DC conductivity of PPy was found to increase by four orders of magnitude on r GO doping . The nanocomposites were explored for field emission and the results fitted well to the FowlerNordheim model of emission . The maximum values of the current density 26A cm
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A novel one pot synthesis of polypyrrole PPy reduced graphene oxide r GO nanocomposites for assessing their potential as a cold cathode material in field emission based devices is reported. Field emission scanning electron microscopy X ray diffraction Fourier transform infrared spectroscopy and Raman spectroscopy indicated successful intercalation of PPy within r GO sheets. The nanocomposites were explored for field emission and extremely good field emitters with long term emission current stability were obtained. The nanocomposites showed very small turn on field 1. 3 V m corresponding to high values of current density 26 A cm. and field enhancement factor. 8.0 10. for PPy r GO
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S0022369719314647
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Two dimensional layered materials like graphene phosphorene and silicene are promising materials for use as anodes in Li and Na ion batteries . However during synthesis of these materials point defects single vacancy divacancy or StoneWales type are quite likely to form and to change the performance as an anode material . In this study the influences of these defects on Na adsorption performance in black phosphorene are investigated . We conclude that these defects could affect performance of phosphorene as an anode material negatively in the case of DV 2 SV and SW 2 defects but positively for DV 1 and SW 1 defects . This impact on the performance is greatest in both paths for SW 2 defects with the diffusion coefficient almost zero . However the SW 1 and DV 1 defects could improve Na diffusion in phosphorene making these desirable for phosphorene as anode material for Na ion batteries .
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Influence of Na atom on point defect phosphorene is investigated. First principles calculations within the DFT formalism are used. Electronic structure of defected phosphorenes in presence of Na are investigated. Diffusion of Na atoms in point defect phosphorene is investigated.
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S0022369719314738
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The surface interface energy is a key parameter for determining the properties of nanomaterials . Many studies have investigated the surface energy for free standing nanoparticles but the interface energy of embedded nanoparticles requires further analysis . In this study we developed a model of the size dependent interfacial energy for embedded metallic nanoparticles in terms of the size dependent cohesive energy . The model was applied to PbCu PbAl and AgNi systems as three examples and the results were compared with those obtained using previously developed models and the available experimental data . Depending on the system considered the interface energy could increase or decrease as the particle size decreased . Similarly the dependence of the interface energy on the temperature was also related to the system considered where the interface energy could decrease or increase as the temperature increased . The results also showed that there was a critical value for interface coherency where the effect of size on the interface energy was reversed .
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Model of size dependent interfacial energy of embedded metallic nanoparticles. Effects of size shape temperature and interface coherency on interface energy. Proposed model agrees better with experimental data than previous models.
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S0022369719314805
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We investigated the electrochemical performance of reduced graphene oxide carbon nanotube hybrid papers as binder free anodes for potassium ion batteries . RGO CNT hybrid papers were fabricated by vacuum filtration and thermal reduction . The potassium ion storage ability of rGO paper was significantly enhanced by CNT incorporation and the electrochemical performance of the hybrid papers was related to the weight ratio of CNTs . The optimal rGO CNT 30 paper can deliver an initial reversible discharge capacity of 351 and 223mAhg
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RGO CNT hybrid papers were fabricated by vacuum filtration and thermal reduction. The potassium ion storage ability of rGO paper was significantly enhanced by CNT incorporation. RGO CNT 30 paper delivered a reversible capacity of 232mAhg. at a current density of 50mAg. respectively. The enhanced performance of rGO CNT hybrid papers was attributed to the formation of a 3D conductive carbon network.
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S0022369719314994
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In this study nanostructured cerium oxide with an average crystallite size of 5nm was synthesized using a chemical co precipitation method with cerium nitrate hexahydrate and sodium hydroxide as the starting materials . Deoxyribonucleic acid powder was used as the biological capping agent . The structural characteristics of the prepared nanoparticles were determined using X ray diffraction high resolution transmission electron microscopy X ray photoelectron spectroscopy Raman spectroscopy Fourier transform infrared and ultravioletvisible spectroscopy . The antioxidant efficacy was estimated by measuring the scavenging activities of free radicals such as superoxide hydroxyl nitric oxide and hydrogen peroxide . The nanostructured ceria synthesized with the assistance of DNA scavenged all four oxidizing species well irrespective of the ratio of
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Novel nanoceria synthesis method proposed using DNA as a capping agent. Synthesis of well dispersed nano ceria measuring 5nm in diameter. Confirmed effect of the crystal planes on the high antioxidant activity. DNA assisted synthesis controlled the morphology and crystal facets of nanoceria.
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S0022369719315173
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Dendritic nanomaterial exhibits a unique structure and an excellent performance . Silicon carbide nanowires with dendritic structure were synthesized for the first time by using facile methods that combine electroless plating Fe with carbon thermal reduction . The dendritic SiC nanowires show an improved microwave absorption performance compared with their linear counterparts . The maximum reflection loss of these nanowires reaches 51.5dBat a frequency of 10.3GHz and an effective EM wave absorption band R
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Dendritic SiC nanowires were synthesized for the first time by employing the strategy of catalyst inducing nucleation. The dendritic SiC nanowires have branch like structure explained by the vaporliquidsolid mechanism. The dendritic SiC nanowires exhibit superior EM wave absorption than linear SiC nanowires. The effects of structure on the enhanced performance are thoroughly explored.
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S0022369719315410
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Excessive heat stability poor kinetics of hydrogen absorption and desorption reaction are viewed as the major setbacks for the Mg based hydrogen storing materials application . The microstructures of samples Mg
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MgYNiCu based alloys with nanocrystalline structures were fabricated by melt spinning. Substituting Y for Mg leads to the improvement of thermodynamic property. Increasing Y content brings about the promotion of dehydrogenation kinetics of the alloys. Substituting Y for Mg enables the steadiness of experimental hydride to decline.
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S0022369719315793
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In this study hydrogen generation from sodium borohydride was achieved via disulfonated poly copolymers . Protons on the sulfone groups of copolymers catalyzed the hydrolysis of sodium borohydride and produced hydrogen . The hydrogen generation rate was affected by the disulfonation degree which is an indication of the amount of sulfone groups in the copolymer . The rate showed an increment as the disulfonation degree increased . Additionally the hydrogen generation rate was a function of both the copolymer amount and borohydride concentration . Moreover the reaction had relatively low activation energy and was calculated from the Arrhenius plot as 19.2kJmol
|
The hydrogen generation rate is a function of sulfonation degree of copolymers. The hydrogen generation rate increases with polymer amount utilized. The hydrogen generation rate increases with sodium borohydride concentration. Copolymers are highly reusable and can preserve catalytic activity up to 25 runs.
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S0022369719315926
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The present paper examines molecular motion mechanisms in lamellar molecular crystals of undecylenic acid . Thermophysical dielectric and infrared spectroscopy methods were used to demonstrate the presence of a relaxation process in crystals of undecylenic acid in the temperature range of 60 to 10 . The process is thought to be due to the free rotation of carboxylic groups after dissociation of dimeric rings and the nucleation of topological solitons . Topological solitons originate once the carboxylic groups begin to rotate freely .
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Relaxation process observed in crystals of undecylenic acid. Relaxation is due to free rotation of carboxylic groups after dimeric rings dissociate. Topological solitons originate once the carboxylic groups begin to rotate freely.
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S002236971931594X
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In our previous study cetyltrimethylammonium bromide admicelles on polystyrene microspheres for the adsolubilization of phenanthrene had been developed . In this work CTAB admicelles modified on magnetic PS nanocomposites was used as a novel adsorbent to facilitate magnetic separation . Magnetic PS nanoparticles were synthesized by miniemulsion polymerization in which the emulsifier was polyvinylpyrrolidone and an oil phase consisted of oleate modified Fe
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PVP as an emulsifier in synthesis of MPS NPs. Large admicelles formation. Phenanthrene adsorption by adsolubilization.
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S0022369719316403
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Two dimensional CuO ZnO hybrid nanostructures were prepared by using a simple chemical approach and thoroughly investigated by FESEM X ray photoelectron spectroscopy HRTEM UVVis absorption spectroscopy and X ray diffraction . The photocatalytic decomposition of organic dyes was evaluated using the prepared 2D CuO ZnO hybrid nanostructures as photocatalysts under sunlight irradiation . Photocatalytic degradation assisted by 2D CuO ZnO nanohybrids showed remarkably improved efficiency than pristine nanosheets of CuO and completely decolorized MB and MO dyes in just 20min . Photocatalytic degradation of toxic 4 nitrophenol was also investigated in the presence of prepared nanostructures and 2D CuO ZnO nanohybrids illustrated better activity over pristine CuO nanosheets . The observed superior photocatalytic performance of 2D CuO ZnO nanohybrids is ascribed to the inhibited charge carrier recombination and improved light utilization because of formation of p n nanoheterojunctions of CuO and ZnO . A possible mechanism and role of radicals participating in photocatalytic degradation of dyes were also proposed .
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2D CuO ZnO nanohybrids were synthesized by a facile wet chemical route. FESEM TEM and HRTEM studies revealed 2D CuO ZnO hybrid nanostructures. 2D CuO ZnO nanohybrids exhibited excellent photocatalytic activities for degrading 4 nitrophenol and organic dyes. Excellent photocatalytic performance of 2D CuO ZnO nanohybrids is attributed to their improved utilization of sunlight and p n nanoheterojunctions.
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S0022369719316439
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Multifunctional transition metal sulphide electrocatalysts were synthesized employing hydrothermal method with stabilization at 180C for 24h for both supercapacitors and water splitting applications . Rhombohedral MoS
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High specific capacitance of 513F g at 0.5 A g was achieved for MoS. Stability of 98 was achieved for MoS. after 1000 cycles of galvanostatic charging and discharging. A high current density of 442mA g was achieved at 10mV s. After a chronoamperometry test for 12h 100 oxygen evolution reaction activity was obtained for MoS. The MoS. electrode is highly recommended as an efficient electrode for energy applications.
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S002236971931652X
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Because of the high theoretical capability surpassing other anode materials silicon has been regarded as the most potential anode material for the next generation lithium ion batteries . In this work the amorphous SiO
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SiO. nanosheets can be extracted from abundant and low cost kaolinite. Si nanosheets can be obtained with a high yield via magnesium thermal reaction. High capacity and long cycling stability can be achieved.
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S0022369719316580
|
The application of photovoltaic technology is limited due to scarcity and toxicity of the efficient materials used for the energy conversion process . Nitridebased binaries can resolve these challenges by their abundance and nontoxicity as well as flexible structureproperty correlations emerging from the moderate electronegativity of the nitrogen atom . In this work thin films of earth abundant tin nitride Sn
|
Experimental strategy of simultaneous control over multiple processing parameters was adopted. Influence of preferred orientation and defects on conduction band convergence was explored. Single step band converging process optimized both the bandgap and absorption coefficient. Thermoelectric parameters were integrated with optical analyses to explore band evolution.
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S0022369719316762
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As a sensitive analytical technique surface enhanced Raman scattering is widely used in spectral analysis single molecule detection and biological chemical sensors . Noble metal nanostructures have sensitive SERS properties and usually act as SERS substrates . Moreover semiconductors also possess SERS properties and when the semiconductors are combined with noble metals this can not only enhance the SERS signal but also introduce additional properties . Therefore in this investigation SiO
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A novel FE imprinted SERS sensor based on SiO. @TiO. @Ag composites was prepared. SiO. @TiO. possessed the property of self cleaning and could be recycled. SiO. @TiO. had a very low detection limit and are a new way to determine FE.
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S0022369719316853
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A p type transition metal oxide copper oxide was modified with nitrogen doped carbon quantum dots to fabricate an effective CuO NCQDs solar driven photo catalyst . The fabrication of single phase monoclinic CuO was confirmed by XRD . SEM images showed the leaf like morphology for CuO which appeared rough and densely packed in CuO NCQDs composites . TEM images of CuO NCQDs shows slightly distorted nano leaves with NCQDs dispersed on them . HRTEM of CuO NCQDs shows fringes with characteristic planes confirming that the addition of NCQDs has not distorted the crystal structure of CuO . SAED of CuO NCQDs further confirms the crystalline nature of the as synthesized composite photo catalyst by exhibiting bright diffraction rings . These results further supported the XRD data . EDS spectra of NCQDs and CuO NCQDs confirm the formation of pure nitrogen doped carbon quantum dots and Cu N C and O atoms confirming that NCQDs are well incorporated on CuO Nano leaves . UVVis spectra showed a slight increase of band gap energies due to quantum confinement effects . PL spectra exhibited decreased photoluminescence intensity indicating suppression of recombination rate . The developed photocatalyst was applied for the degradation of harmful dye methyl orange . The composite catalyst showed superior degradation efficiency as compared to pure CuO nano leaves attributed to enhanced visible light absorption and better charge separation ability due to introduction of NCQDs .
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NCQDs based highly solar efficient photo catalyst is fabricated by facile route of wet chemical method. The surface roughness of CuO nano leaves is observed due to NCQDs which provide more active sites. The quantum confinement effects of NCQDs tuned the bandgap of the CuO nanostructures. NCQDs modified photo catalyst highly quenched photoluminescence indicating efficient charge separation. This enhanced photocatalytic activity of CuO NCQDs is attributed to the availability of active sites and charge separation.
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S0022369719317068
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The energy levels of the quantum dots are evaluated by using Quantum Genetic Algorithm procedure and Hartree Fock Roothaan method . Based on the calculated energies and wave functions static dipole polarizability oscillator strength and electric field gradient of helium helium like quantum dots are calculated as a perturbative calculation . It is worth to note that impurity charge and dot radius have a strong effect on the dipole polarizability the oscillator strength and the electric field gradient . In small dot radii since the spatial confinement effect is dominant the polarizability of system is very weak . The polarizability increases monotonically with the increase of dot radius and then reaches a saturation value in large dot radii . On the other hand the electric field gradient increases as dot radius decreases .
|
Static dipole polarizability of helium helium like quantum dots is investigated. Electric field gradient of quantum dots is carried out. Energy states and wave functions of quantum dots are obtained from the Quantum Genetic Algorithm and Hartree Fock Roothaan method.
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S002236971931707X
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CuS CuO nanowire heterostructures grown on copper mesh have been successfully synthesized by a liquidsolid reaction at room temperature followed by annealing . The proposed structure has been verified by X ray diffraction analysis . Scanning electron microscopy images have indicated that the density and diameter of CuS nanoparticles on CuO nanowires can be tuned by controlling the duration of sulfonation with Na
|
CuS CuO Cu nanowire heterostructures have been fabricated by a sequence of sulfonation and annealing. The formation of CuS CuO heterostructures improves the photocatalytic activity of CuO Cu. The amount of CuS on a CuO surface affects the catalytic activity of CuS CuO Cu.
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S0022369719317093
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In this article we investigate the effect of various antidote defects on the electronic properties and current characteristics of an armchair Germanene nanoribbon using density functional theory and non equilibrium Green s function method . The defected AGeNRs are introduced by setting antidote topologies in the pristine nanoribbons resulting in antidote super lattice of AGeNRs . It is found that new electronic properties appear due to the presence of defects . The obtained results indicate that bandgap of the defected AGeNRs can be increased or decreased in different cases . Moreover the transport properties are analyzed based on the various defect locations in the AGeNR when the ribbon is utilized as the channel of a tunneling field effect transistor . Based on our results it is found that the presence of antidote defects leads to reduction or increase in the current drifting the Dirac point and decreasing or increasing the minimum or off state current .
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First principles study is carried out to investigate impact of antidotes on transport properties of Germanene nanoribbons. Four topologies of antidotes are introduced and bandstructures are obtained and compared with the pristine case. The bandgap size and the carrier effective mass is extracted analyzed and compared from the bandstructures. The transport properties are analyzed when defected ribbon is utilized as the channel of a tunneling field effect transistor. The impact of position of antidotes on the electronic properties is investigated both in lateral and transverse direction.
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S0022369719317238
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Quantification of bioactive molecules through voltammetry techniques is significant over the past decades due to its adaptability and precision of assessment at the trace level . The present study involves a sensitive voltammetric process for the detection of nimesulide was developed at nanoclay blended carbon paste electrode applying voltammetric techniques such as cyclic voltammetry and square wave voltammetry in a media of pH 7.0 phosphate buffer solution . The proposed nanosensor increased peak current by a less negative shift in the potential due to electro catalytic properties of nanoclay particles . The persuade of physicochemical constraint on the voltammetric behavior of NIM were studied . Based on the obtained results number of protons and electrons participated in the electrooxidation reaction heterogeneous rate constant value detection and quantification limits were also calculated . The proposed electrode showed lower detection limit value of 1.01nM and hence can be used to determine NIM in tablet and urine samples with good recovery values .
|
Novel nanoclay based electrodes were efficiently used to determine nimesulide. Nanoclay based sensor showed excellent sensitivity selectivity and low value 1.01x10 9 of limit of detection. Nanosensor has potential to apply in the human urine samples with excellent recovery values.
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S0022369719317354
|
The usage of semiconductor photocatalyst has been received great attention in recent years due to their wide application in photocatalytic water splitting and degradation of pollutants in waste water and environmental remediation application etc . In this study we demonstrated the efficient synergistically piezo phototronic effect of ZnO Ag
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ZnO Ag. S hybrid has been synthesized using hydrothermal and SILAR methods. Physico chemical characterizations were adopted for the confirmation of the catalyst. The piezo phototronic performance using organic dye de colorization was investigated. The piezo phototronic catalyst ZnO Ag. S exhibited an excellent degradation of Rh B dye upon photon and ultrasound irradiation with 7 fold increment in rate kinetics with bare photocatalyst ZnO .
|
S0022369719317536
|
In the present work a novel heterogeneous catalytic system involving palladium complex as moisture and air stable organoselenium ligand supported on Fe
|
An organoselenium palladium complex stabilized on Fe. nanoparticle was prepared. Fe. @SiO. T Se Pd II showed excellent activity in SuzukiMiyaura coupling reaction. Catalyst recycled five times without discernible decrease in catalytic activity.
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S0022369719317573
|
Band structure and optical spectrum of hexagonal and tetragonal ScN monolayers are studied using density functional theory . More accurate and reliable mBJ GGA method is applied to find the compressive and tensile strain effects on electronic and optical properties of these structures . Results show different band structure and optical behavior of these models and considerable effects of tension on their physical properties .
|
Impact of Stress and strain on electronic and optical properties of h ScN and t ScN monolayers are studied. mBJ GGA method is used to find more accurate results for the band gap. In contrast to the t ScN the h ScN is only stable under tensile strain. The threshold of the absorption spectrum depends on strain values.
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S0022369719317883
|
A simple aqueous solution process was used for the synthesis of Cu loaded ZnO nanorod structures in which highly crystalline and hexagonal wurtzite ZnO cubic CuO and Cu
|
Crystalline hexagonal wurtzite ZnO cubic CuO and Cu. O phases coexist in Cu loaded ZnO nanorods grown by simple aqueous solution process. Band gap narrowing via hybridization of O 2p with Cu 3d bands in ZnO Cu. O promotes visible light absorption. Specific band positions of ZnO Cu. O and CuO help migration of charges and impede carrier recombination. Available electrons and holes produce O. and OH radicals for dye degradation. Optimized Cu loading results in superior photocatalytic activity in ZnO Cu. O heterostructure nanocomposites.
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S0022369719318025
|
The first principles calculations within generalized gradient approximation method are employed to study the structural electronic magnetic and mechanical properties of d
|
The Heusler alloys XF. X Be Mg Ca Sr Ba have half metallic ferromagnetic feature. The Heusler alloys XF. X Be Mg Ca Sr Ba are thermodynamic and mechanical stable. The total magnetic moment of the XF. X Be Mg Ca Sr Ba alloys are an integer of 1. f.u. Their HM properties are robust under the effect of hydrostatic strain and tetragonal strain.
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S0022369719318141
|
Spiral nanostructures with many potential applications in next generation high tech industries can show outstanding mechanical electrical and thermal properties thanks to their special topologies . In this study we report a detailed analysis of heat transport in graphene spiral nanostructures . The non equilibrium molecular dynamics simulation is used to investigate the thermal conductivity of the spirals in both axial and radial directions for different geometries . The results reveal that with increasing widths of the graphene spirals effective thermal conductivity in the axial direction and the thermal conductivity in the radial direction increase . But with increasing the lengths of the graphene spirals only the axial thermal conductivity increases . Furthermore the axial tensile strain and the addition of an extra layer to form a double layer spiral structure have positive effects on increasing the thermal conductivity in the axial direction . Moreover the results show that the thermal conductivity in radially inward and outward directions differ from each other arising from asymmetricity between the two radial directions where the heat flux prefers the inward direction .
|
Thermal conductivity of graphene spirals in axial direction. Thermal conductivity and rectification in radial direction of graphene spirals. Strain effects on the thermal conductivity of graphene spirals.
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S0022369719318165
|
MAX phases are a large group of nanolaminated carbide and nitride materials of immense scientific and technological interest . Materials of this class are known as metallic ceramics as they show a remarkable combination of metallic and ceramic properties at the same time . To date about 80 MAX phases have been synthesized and more than 650 MAX phases are predicted to be synthesized in the future . At present there are nine MAX phase nanolaminates that show superconducting transitions at low temperatures . Although MAX phases have been studied extensively thorough understanding of the correlation between electronic structure and physical properties is still somewhat limited . Here we review the physical properties of superconducting MAX phases on the basis of electronic structures using first principles density functional theory .
|
Superconducting MAX phases are studied comprehensively. Nb. AsC is mechanically superior to the other phases and Lu. SnC is soft and machinable. Lu. SnC is predicted to be a thermal barrier coating material. Ti. InN is predicted to be a better coating material for preventing solar heating. Populated A layers may be the reason for the existence of superconductivity in only 211 MAX phases.
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S0022369719318232
|
Supercapacitors have been extensively used in power storage and power management components for its outstanding performances in recent years . In this paper the novel 3D rose like Ni
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Ni OH. rGO composites have been successfully synthesized by a simple hydrothermal method. The prepared Ni OH. rGO composites exhibited a rose like morphology. Graphene distributed uniformly around the interior of Ni OH. instead of acting as a substrate. The Ni OH 2 rGO composite exhibits high cycling stability.
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S0022369719318451
|
Modification of semiconductor materials by polyoxometalates is a promising strategy for increasing their photoelectrocatalytic activity . In this work we synthesized POM modified CdS composite nanocrystals based on three kinds of Keggin type mixed addendum Mo W POMs Ag
|
The semiconductor properties of three Keggin type mixed addendum Mo W polyoxometalates were revealed for the first time. CdS polyoxometalate composite nanocrystals show photoelectrocatalytic performance superior to that of pure CdS nanocrystals. The CdS PMo. composite nanocrystals exhibit the highest efficiency for the photoelectrocatalytic oxidation of As III .
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S0022369719318633
|
Modulation spectroscopy is a well established method for the study of optical transitions in semiconductors and has been a valuable asset for the verification of theoretical band structure calculations . The most important aspect of this method is its ability to render clear spectral features with no prior assumptions . One modulation technique is electroabsorption in which the transmittance of a sample is modulated by the application of a time varying electric field while light is incident on the sample . In this work a modified form of electroabsorption was investigated in which the electric field was applied at the interface between the sample and a transparent conducting layer . This technique was applied to investigate the optical transitions in tungsten trioxide WO
|
A new modulation spectroscopy technique is devised. It is based on modulating the transmittance through a material. The method is applied to WO. films deposited by RF sputtering. Sharp optical spectra were obtained and compared to theoretical calculations.
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S0022369719318645
|
A device consisting of a multidomain liquid crystal polymer network sandwiched between a continuous electrode and a perforated silver electrode shows strong surface deformations upon application of an electric field between the electrodes . Here a new method is presented for the preparation of such a device in which a silver film with circular holes of a well controlled diameter was made by evaporating silver onto a monolayer of polystyrene spheres . Due to multilayer defects of the polystyrene microparticle lithography template larger combined holes were present which provided interesting information about the effect of pore size on the deformation behavior . The results were compared to an electrostatic field distribution from which the conclusion could be drawn that there is a minimum hole size that allows deformation . This knowledge is important for the development of applications for this kind of device as the aspect ratio of the deformations is of crucial importance for effects such as switchable wetting and self cleaning .
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A device with electrically driven surface deformations based on a multidomain liquid crystal polymer network was prepared. The required perforated top electrode was prepared by evaporating silver onto a monolayer of polystyrene spheres. Multilayer defects led to holes of various sizes providing information on the effect of hole size on surface deformation. Static electric field distributions of variously sized holes were simulated to explain the minimum hole size for deformation.
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S0022369719318670
|
In this study N doped platelet like metal loaded Zr SBA 15 was synthesized and employed for reducing 4 nitrophenol to remove this contaminant from water . Dopamine hydrochloride was used as a novel CN source for the modification of ZrSBA 15 . The N doping process occurred readily at a low temperature due to the polymerization of dopamine which could save energy and simplify the experimental fabrication of catalysts . In addition polydopamine can immobilize Pd ions in a facile manner and the trapped Pd ions are reduced to Pd nanoparticles due to the reducibility of the polydopamine polymer . The utilization of dopamine allows the catalyst to be obtained in a facile and cost effective synthetic process while the production of the CN layer as well as the reduction and immobilization of the Pd ions can occur simultaneously . Characterization of the product showed that the catalyst had a platelet like structure after decoration with elemental Zr which enhanced the catalytic reaction compared with the natural fiber like SBA 15 . The optimal Pd loading capacity was determined as 3.0wt and the materials obtained could reduce 4 nitrophenol to 4 aminophenol within 120s with a conversion ratio above 90 .
|
Mussel inspired surface modification of ZrSBA 15 with polydopamine PDA . PDA facilitated immobilization and reduction of Pd nanoparticles. PDA transformed. into nitrogen doped carbon layers. Pd ZrSBA 15 exhibited excellent catalytic performance in reduction of 4 nitrophenl.
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S0022369719319055
|
Pure and co doped multiferroic bismuth ferrite nanoparticles were synthesized by the sol gel method . Samarium and cobalt were used as co dopants in BFO . The co doped composites had the formula Bi
|
Bismuth ferrite co doped with Sm and Co was synthesized and the crystallite size was found to decrease from 66 to 23 nm. The co doped samples showed enhanced saturation magnetization and remanent magnetization of 3.2 and 1.5 emu g respectively. The maximum polarization and remanent polarization were 12.5 and 7.5 C cm2 respectively. The resistive properties decreased considerably at low frequency and remained almost constant at high frequency. AC conductivity increased nonlinearly at high frequency and exhibited nearly invariable behavior at low frequency.
|
S0022369719319134
|
In the present investigation we have designed highly active titanium dioxide nanohybrids modified by various additives such as niobium oxide Nb
|
The TiO. Nb. SnO. RGO TiO. Ceramic SnO. RGO TiO. Nb. SnO. and TiO. Ceramic SnO. nanocomposites were synthesized. Photocatalytic degradation of organic dyes was estimated under visible light. TiO. Nb. SnO. RGO exhibits remarkable photocatalytic activity and reusability.
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