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= = Production = =
Europium is associated with the other rare earth elements and is , therefore , mined together with them . Separation of the rare earth elements is a step in the later processing . Rare earth elements are found in the minerals bastnäsite , loparite , xenotime , and monazite in mineable quantities . The first two are orthophosphate minerals LnPO
4 ( Ln denotes a mixture of all the lanthanides except promethium ) , and the third is a fluorocarbonate LnCO3F . Monazite also contains thorium and yttrium , which complicates handling because thorium and its decay products are radioactive . For the extraction from the ore and the isolation of individual lanthanides , several methods have been developed . The choice of method is based on the concentration and composition of the ore and on the distribution of the individual lanthanides in the resulting concentrate . Roasting the ore and subsequent acidic and basic leaching is used mostly to produce a concentrate of lanthanides . If cerium is the dominant lanthanide , then it is converted from cerium ( III ) to cerium ( IV ) and then precipitated . Further separation by solvent extractions or ion exchange chromatography yields a fraction which is enriched in europium . This fraction is reduced with zinc , zinc / amalgam , electrolysis or other methods converting the europium ( III ) to europium ( II ) . Europium ( II ) reacts in a way similar to that of alkaline earth metals and therefore it can be precipitated as carbonate or is co @-@ precipitated with barium sulfate . Europium metal is available through the electrolysis of a mixture of molten EuCl3 and NaCl ( or CaCl2 ) in a graphite cell , which serves as cathode , using graphite as anode . The other product is chlorine gas .
A few large deposits produce or produced a significant amount of the world production . The Bayan Obo iron ore deposit contains significant amounts of bastnäsite and monazite and is , with an estimated 36 million tonnes of rare earth element oxides , the largest known deposit . The mining operations at the Bayan Obo deposit made China the largest supplier of rare earth elements in the 1990s . Only 0 @.@ 2 % of the rare earth element content is europium . The second large source for rare earth elements between 1965 and its closure in the late 1990s was the Mountain Pass rare earth mine . The bastnäsite mined there is especially rich in the light rare earth elements ( La @-@ Gd , Sc , and Y ) and contains only 0 @.@ 1 % of europium . Another large source for rare earth elements is the loparite found on the Kola peninsula . It contains besides niobium , tantalum and titanium up to 30 % rare earth elements and is the largest source for these elements in Russia .
= = Compounds = =
Europium compounds tend to exist trivalent oxidation state under most conditions . Commonly these compounds feature Eu ( III ) bound by 6 – 9 oxygenic ligands , typically water . These compounds , the chlorides , sulfates , nitrates , are soluble in water or polar organic solvent . Lipophilic europium complexes often feature acetylacetonate @-@ like ligands , e.g. , Eufod .
= = = Halides = = =
Europium metal reacts with all the halogens :
2 Eu + 3 X2 → 2 EuX3 ( X = F , Cl , Br , I )
This route gives white europium ( III ) fluoride ( EuF3 ) , yellow europium ( III ) chloride ( EuCl3 ) , gray europium ( III ) bromide ( EuBr3 ) , and colorless europium ( III ) iodide ( EuI3 ) . Europium also forms the corresponding dihalides : yellow @-@ green europium ( II ) fluoride ( EuF2 ) , colorless europium ( II ) chloride ( EuCl2 ) , colorless europium ( II ) bromide ( EuBr2 ) , and green europium ( II ) iodide ( EuI2 ) .
= = = Chalcogenides and pnictides = = =
Europium forms stable compounds with all of the chalcogens , but the heavier chalcogens ( S , Se , and Te ) stabilize the lower oxidation state . Three oxides are known : europium ( II ) oxide ( EuO ) , europium ( III ) oxide ( Eu2O3 ) , and the mixed @-@ valence oxide Eu3O4 , consisting of both Eu ( II ) and Eu ( III ) . Otherwise , the main chalcogenides are europium ( II ) sulfide ( EuS ) , europium ( II ) selenide ( EuSe ) and europium ( II ) telluride ( EuTe ) : all three of these are black solids . EuS is prepared by sulfiding the oxide at temperatures sufficiently high to decompose the Eu2O3 :
Eu2O3 + 3 H2S → 2 EuS + 3 H2O + S
The main nitride is europium ( III ) nitride ( EuN ) .
= = History of study = =
Although europium is present in most of the minerals containing the other rare elements , due to the difficulties in separating the elements it was not until the late 1800s that the element was isolated . William Crookes observed the phosphorescent spectra of the rare elements and observed spectral lines later assigned to europium .
Europium was first found in 1890 by Paul Émile Lecoq de Boisbaudran , who obtained basic fractions from samarium @-@ gadolinium concentrates which had spectral lines not accounted for by samarium or gadolinium . However , the discovery of europium is generally credited to French chemist Eugène @-@ Anatole Demarçay , who suspected samples of the recently discovered element samarium were contaminated with an unknown element in 1896 and who was able to isolate it in 1901 ; he then named it europium .
When the europium @-@ doped yttrium orthovanadate red phosphor was discovered in the early 1960s , and understood to be about to cause a revolution in the color television industry , there was a scramble for the limited supply of europium on hand among the monazite processors , as the typical europium content in monazite is about 0 @.@ 05 % . However , the Molycorp bastnäsite deposit at the Mountain Pass rare earth mine , California , whose lanthanides had an unusually high europium content of 0 @.@ 1 % , was about to come on @-@ line and provide sufficient europium to sustain the industry . Prior to europium , the color @-@ TV red phosphor was very weak , and the other phosphor colors had to be muted , to maintain color balance . With the brilliant red europium phosphor , it was no longer necessary to mute the other colors , and a much brighter color TV picture was the result . Europium has continued to be in use in the TV industry ever since as well as in computer monitors . Californian bastnäsite now faces stiff competition from Bayan Obo , China , with an even " richer " europium content of 0 @.@ 2 % .
Frank Spedding , celebrated for his development of the ion @-@ exchange technology that revolutionized the rare earth industry in the mid @-@ 1950s , once related the story of how he was lecturing on the rare earths in the 1930s when an elderly gentleman approached him with an offer of a gift of several pounds of europium oxide . This was an unheard @-@ of quantity at the time , and Spedding did not take the man seriously . However , a package duly arrived in the mail , containing several pounds of genuine europium oxide . The elderly gentleman had turned out to be Herbert Newby McCoy who had developed a famous method of europium purification involving redox chemistry .
= = Applications = =
Relative to most other elements , commercial applications for europium are few and rather specialized . Almost invariably , they exploit its phosphorescence , either in the + 2 or + 3 oxidation state .
It is a dopant in some types of glass in lasers and other optoelectronic devices . Europium oxide ( Eu2O3 ) is widely used as a red phosphor in television sets and fluorescent lamps , and as an activator for yttrium @-@ based phosphors . Color TV screens contain between 0 @.@ 5 and 1 g of europium oxide . Whereas trivalent europium gives red phosphors , the luminescence of divalent europium depends on the host lattice , but tends to be on the blue side . The two classes of europium @-@ based phosphor ( red and blue ) , combined with the yellow / green terbium phosphors give " white " light , the color temperature of which can be varied by altering the proportion or specific composition of the individual phosphors . This phosphor system is typically encountered in helical fluorescent light bulbs . Combining the same three classes is one way to make trichromatic systems in TV and computer screens . Europium is also used in the manufacture of fluorescent glass . One of the more common persistent after @-@ glow phosphors besides copper @-@ doped zinc sulfide is europium @-@ doped strontium aluminate . Europium fluorescence is used to interrogate biomolecular interactions in drug @-@ discovery screens . It is also used in the anti @-@ counterfeiting phosphors in euro banknotes .
An application that has almost fallen out of use with the introduction of affordable superconducting magnets is the use of europium complexes , such as Eu ( fod ) 3 , as shift reagents in NMR spectroscopy . Chiral shift reagents , such as Eu ( hfc ) 3 , are still used to determine enantiomeric purity .
A recent ( 2015 ) application of europium is in quantum memory chips which can reliably store information for days at a time ; these could allow sensitive quantum data to be stored to a hard disk @-@ like device and shipped around the country .
= = Precautions = =
There are no clear indications that europium is particularly toxic compared to other heavy metals . Europium chloride , nitrate and oxide have been tested for toxicity : europium chloride shows an acute intraperitoneal LD50 toxicity of 550 mg / kg and the acute oral LD50 toxicity is 5000 mg / kg . Europium nitrate shows a slightly higher intraperitoneal LD50 toxicity of 320 mg / kg , while the oral toxicity is above 5000 mg / kg . The metal dust presents a fire and explosion hazard .
= North @-@ Eastern Area Command ( RAAF ) =
North @-@ Eastern Area Command was one of several geographically based commands raised by the Royal Australian Air Force ( RAAF ) during World War II . For most of its existence it covered central and northern Queensland , and Papua New Guinea . It was formed in January 1942 from the eastern part of the former Northern Area Command , which had covered the whole of northern Australia and Papua . Headquartered at Townsville , Queensland , North @-@ Eastern Area Command was primarily responsible for air defence , aerial reconnaissance and protection of the sea lanes within its boundaries . Aircraft under its control took part in the battles of Rabaul , Port Moresby and Milne Bay in 1942 , and the landings at Hollandia and Aitape in 1944 . The command continued to operate following the end of the war , before its responsibilities were subsumed in 1954 by the RAAF 's new functional command @-@ and @-@ control system ; the headquarters was disbanded two years later .
= = History = =
= = = World War II = = =
North @-@ Eastern Area Command was formed at Townsville , Queensland , on 15 January 1942 , taking over the eastern portion of what was previously Northern Area Command . Northern Area had been established on 8 May 1941 as one of the RAAF 's geographically based command @-@ and @-@ control zones , and covered northern New South Wales , Queensland , the Northern Territory , and Papua . The roles of the area commands were air defence , protection of adjacent sea lanes , and aerial reconnaissance . Each area was led by an Air Officer Commanding ( AOC ) responsible for the administration and operations of air bases and units within his boundary .
The outbreak of the Pacific War in December 1941 was the catalyst for Northern Area being split into North @-@ Western Area ( NWA ) and North @-@ Eastern Area ( NEA ) , to counter distinct threats to Northern Australia and New Guinea , respectively . Air Commodore Frank Lukis , formerly in charge of Northern Area , was NEA 's inaugural AOC , taking responsibility for RAAF operations against the Japanese in New Guinea , New Britain and surrounding islands . His headquarters staff numbered 284 . On 20 January 1942 , a force of over 100 Japanese aircraft attacked Rabaul , destroying or badly damaging six CAC Wirraways and killing or wounding eleven crewmen of No. 24 Squadron under Wing Commander John Lerew . The following day , NEA headquarters sent a signal to Lerew ordering him to keep his airfield open , to which Lerew , with only two Wirraways left , replied using the legendary ancient gladiatorial phrase to honour an Emperor : " Morituri vos salutamus " ( " We who are about to die salute you " ) . Ignoring a further message from headquarters to abandon his squadron and escape in a Lockheed Hudson bomber , on 22 January Lerew began evacuating staff to Port Moresby , New Guinea .
No. 33 Squadron , operating ex @-@ Qantas Short Empire flying boats and several smaller transports , was raised in NEA on 19 February 1942 . Earlier that month , Lukis warned higher command of the poor state of preparedness and low morale of Australian Army troops at Port Moresby , due to lack of air cover and apparent lack of interest from government echelons . On 25 February , Nos. 3 and 4 Fighter Sector Headquarters were established to coordinate fighter operations ; they were based at Townsville and Port Moresby respectively . Seventeen P @-@ 40 Kittyhawks of No. 75 Squadron , recently formed at Townsville , were deployed to Port Moresby in mid @-@ March . Commanded by Squadron Leader John Jackson , the squadron suffered heavy losses in the ensuing battle . At one point NEA headquarters gave Jackson permission to withdraw but he refused , and the squadron was eventually credited with destroying thirty @-@ five Japanese aircraft in the air and on the ground , securing Port Moresby until relieved by the 35th and 36th Squadrons of the United States Army Air Forces ( USAAF ) , operating P @-@ 39 Airacobras .
Several USAAF bomber formations operated under NEA 's control in early 1942 , including A @-@ 24 Banshees of the 8th Squadron from Port Moresby , and B @-@ 17 Flying Fortresses of the 435th Squadron ( initially known as the " Kangaroo Squadron " ) from Townsville . As of 20 April , operational authority over all RAAF combat infrastructure , including area commands , was invested in the newly established Allied Air Forces ( AAF ) Headquarters under South West Pacific Area Command ( SWPA ) . One result of this was the integration of USAAF and RAAF staff at area headquarters . According to the official history of the RAAF , though " more a diplomatic gesture than a practical method of war organisation " , it gave personnel from the two services the opportunity to quickly become acclimatised to each other and " in North @-@ Eastern Area , as an example , the atmosphere was happy and the staff extremely cooperative " . Following the Battle of the Coral Sea in May , USAAF units no longer operated under RAAF control in the NEA but were commanded directly by senior American officers of the AAF .
NEA 's operational headquarters , a reinforced concrete bunker known as Building 81 , was completed in May 1942 . Located on Green Street , Townsville , at the base of Castle Hill , it was topped with a suburban house to mislead enemy aircraft . The same month , Eastern Area Command was formed , taking control of units in New South Wales and southern Queensland from Southern Area and NEA . This left NEA in command of Nos. 24 , 33 and 76 Squadrons , as well as No. 3 Fighter Sector Headquarters , at Townsville ; No. 100 Squadron at Cairns ; No. 32 Squadron at Horn Island ; and Nos. 11 , 20 and 75 Squadrons , as well as No. 4 Fighter Sector Headquarters , at Port Moresby . NEA 's boundaries were finetuned on 19 August : a portion of Queensland within the Barkly Tableland and the Haslingden and Heywood districts was assigned to the control of North @-@ Western Area . Lukis handed over command of NEA to Group Captain ( later Air Commodore ) Harry Cobby on 25 August . By the end of the month , the headquarters staff numbered 684 . No. 75 Squadron , replenished after its defence of Port Moresby , and No. 76 Squadron , deployed north from Townsville and also flying Kittyhawks , played what senior Australian Army commanders described as the " decisive " role in the Battle of Milne Bay in New Guinea during August and September 1942 . During the battle , Cobby exercised overall command of the RAAF units from NEA headquarters , while their efforts were coordinated on the ground by Group Captain Bill Garing , NEA 's senior air staff officer .
On 1 September 1942 , No. 9 ( Operational ) Group was formed at Port Moresby as a mobile strike force to move forward with Allied advances in the Pacific , in contrast to the static , defensive nature of the area commands . It took over all units in New Guinea previously operating under NEA Command . NEA initially retained administrative control of No. 9 Group but , on 1 January 1943 , the group was made independent of the area command and its administration became the responsibility of RAAF Headquarters , Melbourne . September 1942 also saw the formation of RAAF Command , led by Air Vice Marshal Bill Bostock , to oversee the majority of Australian flying units in the SWPA . Bostock exercised control of air operations through the area commands , although RAAF Headquarters continued to hold overarching administrative authority over all Australian units . He personally coordinated operations when they involved more than one area command , for instance when the fighter squadrons of both NWA and NEA were required to repulse a major attack . No. 42 ( Radar ) Wing was formed at Townsville in February 1943 , and the following month took control of all radar stations in NEA . As of April 1943 , the area command directly controlled four squadrons tasked primarily with anti @-@ submarine warfare : No. 7 Squadron , flying Bristol Beaufort reconnaissance @-@ bombers out of Ross River ; No. 9 Squadron , a fleet co @-@ operation unit flying Supermarine Seagulls from Bowen ; and Nos. 11 and 20 Squadrons , flying reconnaissance and bombing missions with PBY Catalinas from Cairns .
In early 1943 , Japan was still believed to be capable of invading , or at least bombing , the Torres Strait islands , and NEA had only No. 7 Squadron , now operating from Horn Island , to counter the threat . It was reinforced in April by No. 84 Squadron , flying CAC Boomerang fighters . The same month , No. 72 Wing was formed at Townsville , before deploying to Merauke , New Guinea . Controlling No. 84 Squadron , No. 86 Squadron ( flying Kittyhawks ) , and No. 12 Squadron ( Vultee Vengeance dive bombers ) , the wing was responsible for Torres Strait 's air defence , as well as offensive operations against infrastructure and shipping in Dutch New Guinea . In October , No. 84 Squadron converted to Kittyhawks and transferred to the newly formed No. 75 Wing , which was given responsibility for units at Horn Island , Thursday Island , and Higgins Field on Cape York Peninsula . In February 1944 , No. 75 Wing headquarters moved from Horn Island to Higgins Field , where it was soon joined by other units under its control , Nos. 7 and 23 Squadrons ; the latter operated Vengeances until being declared non @-@ operational in June , prior to re @-@ equipping with B @-@ 24 Liberators for duty in North @-@ Western Area . By May , NEA 's order of battle on the Australian mainland consisted of Nos. 7 , 9 , 13 ( operating Lockheed Venturas from Cooktown ) , 20 and 23 Squadrons .
Cobby served as AOC NEA until November 1943 , handing over to Air Commodore John Summers , who held command for the remainder of the war . By the end of November , NEA headquarters staff numbered 499 , including ninety @-@ seven officers . NEA 's Catalinas joined aircraft of No. 9 Group in support of the US invasion of New Britain in December 1943 and January 1944 . The Catalinas also conducted mine @-@ laying operations around the Timor Sea in the lead @-@ up to the landings at Hollandia and Aitape in April 1944 . In August , No. 76 Wing headquarters , formed at Townsville in January and subsequently based at Cairns , was transferred to Darwin , Northern Territory . There it came under the control of NWA headquarters and oversaw operations by three Catalina squadrons , including No. 20 . The same month , No. 75 Wing was disbanded and its units became the direct responsibility of NEA headquarters . No. 42 Wing disbanded in October 1944 , following a decision to assign control of RAAF radar stations to mobile fighter control units or similar formations . By the end of February 1945 , NEA headquarters staff numbered 743 , including 127 officers . No. 72 Wing headquarters transferred to Townsville in May that year , and disbanded the following month .
= = = Post @-@ war activity and disbandment = = =
Following the end of the Pacific War in August 1945 , SWPA was dissolved and RAAF Headquarters again assumed full control of all its operational formations , including the area commands . By the end of the month , NEA headquarters staff numbered 526 , including ninety @-@ eight officers . The Air Force shrank dramatically as personnel were demobilised and units disbanded ; most of the RAAF 's bases and aircraft employed in operations after the war were situated within Eastern Area 's sphere of control in New South Wales and southern Queensland . In September 1946 , the Chief of the Air Staff , Air Vice Marshal George Jones , proposed reducing the five extant mainland area commands ( North @-@ Western , North @-@ Eastern , Eastern , Southern , and Western Areas ) to three : Northern Area , covering Queensland and the Northern Territory ; Eastern Area , covering New South Wales ; and Southern Area , covering Western Australia , South Australia , Victoria and Tasmania . The Australian Government rejected the plan and the wartime area command boundaries essentially remained in place . By 1949 , NEA headquarters was located in Sturt Street , Townsville . No. 10 Squadron was based at Townsville from March that year , operating Avro Lincolns over the Pacific and Australia 's northern approaches in the maritime reconnaissance and search @-@ and @-@ rescue roles . Air Commodore Ian McLachlan was appointed AOC NEA in September 1951 and served two years in the post before handing over to acting Air Commodore Patrick Heffernan .
Commencing in October 1953 , the RAAF was reorganised from a geographically based command @-@ and @-@ control system into one based on function . In February 1954 , the newly constituted functional organisations — Home , Training , and Maintenance Commands — assumed control of all operations , training and maintenance from North @-@ Eastern Area Command . NEA headquarters remained in existence , but only as one of Home Command 's " remote control points " . It was finally disbanded on 3 December 1956 , and was succeeded by Headquarters RAAF Townsville .
As of 2009 , the former NEA headquarters in Building 81 , Green Street , housed Townsville 's State Emergency Service group .
= = Order of battle = =
As at 30 April 1942 , NEA 's order of battle comprised :
RAAF Station Townsville
No. 24 ( General Purpose ) Squadron
No. 33 ( Transport ) Squadron
No. 76 ( Fighter ) Squadron
RAAF Station Amberley
No. 23 ( General Purpose ) Squadron
RAAF Station Port Moresby
No. 11 ( General Reconnaissance ) Squadron
No. 20 ( General Reconnaissance ) Squadron
No. 32 ( General Reconnaissance ) Squadron
No. 75 ( Fighter ) Squadron
No. 3 Fighter Sector Headquarters , Townsville
No. 4 Fighter Sector Headquarters , Port Moresby
= Cape lobster =
The Cape lobster , Homarinus capensis , is a species of small lobster that lives off the coast of South Africa , from Dassen Island to Haga Haga . Only a few dozen specimens are known , mostly regurgitated by reef @-@ dwelling fish . It lives in rocky reefs , and is thought to lay large eggs that have a short larval phase , or that hatch directly as a juvenile . The species grows to a total length of 10 cm ( 3 @.@ 9 in ) , and resembles a small European or American lobster ; it was previously included in the same genus , Homarus , although it is not very closely related to those species , and is now considered to form a separate , monotypic genus – Homarinus . Its closest relatives are the genera Thymops and Thymopides .
= = Distribution and ecology = =
The Cape lobster is endemic to South Africa . It occurs from Dassen Island , Western Cape in the west to Haga Haga , Eastern Cape in the east , a range of 900 kilometres ( 560 mi ) . Most of the known specimens were regurgitated by fish caught on reefs at depths of 20 – 40 metres ( 66 – 131 ft ) . This suggests that the Cape lobster inhabits rocky substrates , and may explain its apparent rarity , since such areas are not amenable to dredging or trawling , and the species may be too small to be retained by lobster traps .
= = Description = =
Homarinus capensis is considerably smaller than the large northern lobsters of the Atlantic Ocean , Homarus gammarus ( the European lobster ) and Homarus americanus ( the American lobster ) , at 8 – 10 centimetres ( 3 @.@ 1 – 3 @.@ 9 in ) total length , or 4 – 5 cm ( 1 @.@ 6 – 2 @.@ 0 in ) carapace length . Accounts of the colouration of H. capensis are very variable , from tawny , red or yellow to " a rather dark olive " , similar to Homarus gammarus .
Homarinus and Homarus are considered to be the most plesiomorphic genera in the family Nephropidae . Nonetheless , the Cape lobster differs from Homarus in a number of characters . The rostrum of the Cape lobster is flattened , while that of Homarus is rounded in section , and curves upwards at the tip . The three pairs of claws are covered with hairs in Homarinus , while those of Homarus are hairless . The telson tapers along its length in Homarus , but has sides which are nearly parallel in Homarinus . Although no egg @-@ bearing females have been collected , the gonopores ( openings of the oviducts ) of female Cape lobsters are much larger than those of Homarus gammarus and Homarus americanus . This is thought to indicate that Homarinus bears fewer , larger eggs than Homarus , and that either the larvae develop quickly into juveniles after hatching , or that the eggs hatch directly into juveniles .
= = Taxonomy and evolution = =
Cape lobsters are elusive and rare , with only fourteen specimens having been collected between 1792 ( the date of its first description ) and 1992 . These include five males in the collections of the South African Museum ( Cape Town ) , two in the Natural History Museum ( London ) , one in each of the East London Museum , the Rijksmuseum van Natuurlijke Historie ( Leiden ) and the Albany Museum ( Grahamstown ) , and one male and one female in the Muséum national d 'histoire naturelle ( Paris ) . In 1992 , a Cape lobster was discovered at Dassen Island , and the publicity the find generated resulted in more than 20 additional specimens being reported .
The Cape lobster was first described by Johann Friedrich Wilhelm Herbst in 1792 as Cancer ( Astacus ) capensis . It was independently described in 1793 by Johan Christian Fabricius as Astacus flavus , possibly based on the same type specimen . When Friedrich Weber erected the genus Homarus in 1795 , he included Fabricius ' species in it , but this placement was not followed by later authors . The species reached its current classification in 1995 , when the monotypic genus Homarinus was erected by Irv Kornfield , Austin B. Williams and Robert S. Steneck .