Europium 9477 225683883 2008-07-14T21:56:23Z Arkuat 29003 /* Characteristics */ section title according to wikiproject elements {{Elementbox_header | number=63 | symbol=Eu | name=europium | left=[[samarium]] | right=[[gadolinium]] | above=- | below=[[americium|Am]] | color1=#ffbfff | color2=black }} {{Elementbox_series | [[Lanthanoid|lanthanide]]s }} {{Elementbox_periodblock | period=6 | block=f }} {{Elementbox_appearance_img | Eu,63| silvery white }} {{Elementbox_atomicmass_gpm | [[1 E-25 kg|151.964]][[List of elements by atomic mass|(1)]] }} {{Elementbox_econfig | &#91;[[xenon|Xe]]&#93; 4f<sup>7</sup> 6s<sup>2</sup> }} {{Elementbox_epershell | 2, 8, 18, 25, 8, 2 }} {{Elementbox_section_physicalprop | color1=#ffbfff | color2=black }} {{Elementbox_phase | [[solid]] }} {{Elementbox_density_gpcm3nrt | 5.264 }} {{Elementbox_densityliq_gpcm3mp | 5.13 }} {{Elementbox_meltingpoint | k=1099 | c=826 | f=1519 }} {{Elementbox_boilingpoint | k=1802 | c=1529 | f=2784 }} {{Elementbox_heatfusion_kjpmol | 9.21 }} {{Elementbox_heatvaporiz_kjpmol | 176 }} {{Elementbox_heatcapacity_jpmolkat25 | 27.66 }} {{Elementbox_vaporpressure_katpa | 863 | 957 | 1072 | 1234 | 1452 | 1796 | comment= }} {{Elementbox_section_atomicprop | color1=#ffbfff | color2=black }} {{Elementbox_crystalstruct | simple cubic (body centered) }} {{Elementbox_oxistates | 3,2 <br />(mildly [[base (chemistry)|basic]] oxide) }} {{Elementbox_electroneg_pauling | ? 1.2 }} {{Elementbox_ionizationenergies4 | 547.1 | 1085 | 2404 }} {{Elementbox_atomicradius_pm | [[1 E-10 m|185]] }} {{Elementbox_atomicradiuscalc_pm | [[1 E-10 m|231]] }} {{Elementbox_section_miscellaneous | color1=#ffbfff | color2=black }} {{Elementbox_magnetic | no data }} {{Elementbox_eresist_ohmm | ([[room temperature|r.t.]]) (poly) 0.900 µ}} {{Elementbox_thermalcond_wpmkat300k | est. 13.9 }} {{Elementbox_thermalexpansion_umpmk | ([[room temperature|r.t.]]) (poly)<br />35.0 }} {{Elementbox_youngsmodulus_gpa | 18.2 }} {{Elementbox_shearmodulus_gpa | 7.9 }} {{Elementbox_bulkmodulus_gpa | 8.3 }} {{Elementbox_poissonratio | 0.152 }} {{Elementbox_vickershardness_mpa | 167 }} {{Elementbox_cas_number | 7440-53-1 }} {{Elementbox_isotopes_begin | color1=#ffbfff | color2=black }} {{Elementbox_isotopes_decay | mn=150 | sym=Eu | na=[[synthetic radioisotope|syn]] | hl=[[1 E s|36.9 y]] | dm=[[electron capture|ε]] | de=2.261 | pn=150 | ps=[[samarium|Sm]] }} {{Elementbox_isotopes_decay | mn=151 | sym=Eu | na=47.8% | hl=5×10<sup>18</sup> [[year|y]] | dm=[[alpha emission|α]] | de=&nbsp; | pn=147 | ps=[[promethium|Pm]] }} {{Elementbox_isotopes_decay2 | mn=152 | sym=Eu | na=[[synthetic radioisotope|syn]] | hl=[[1 E s|13.516 y]] | dm1=ε | de1=1.874 | pn1=152 | ps1=[[samarium|Sm]] | dm2=[[Beta minus decay|β<sup>-</sup>]] | de2=1.819 | pn2=152 | ps2=[[gadolinium|Gd]] }} {{Elementbox_isotopes_stable | mn=153 | sym=Eu | na=52.2% | n=90 }} {{Elementbox_isotopes_end}} {{Elementbox_footer | color1=#ffbfff | color2=black }} '''Europium''' ({{pronEng|jʊˈroʊpiəm}}) is a [[chemical element]] with the symbol '''Eu''' and [[atomic number]] 63. It was named after the continent [[Europe]]. == Characteristics == Europium is the most reactive of the [[rare earth element]]s; it rapidly oxidizes in air, and resembles [[calcium]] in its reaction with water; deliveries of the metal element in solid form, even when coated with a protective layer of mineral oil, are rarely shiny. Europium ignites in air at about 150 °C to 180 °C. It is about as hard as lead and quite [[ductile]]. == Applications == There are many commercial applications for europium metal, although it has been used to [[dopant|dope]] some types of [[glass]] to make [[laser]]s, as well as for screening for [[Down syndrome]] and some other genetic diseases. Due to its amazing ability to absorb neutrons, it is also being studied for use in nuclear reactors. Europium oxide (Eu<sub>2</sub>O<sub>3</sub>) is widely used as a red [[phosphor]] in [[Cathode ray tube|television sets]] and [[fluorescent lamps]], and as an activator for [[yttrium]]-based phosphors. Whereas trivalent europium gives red phosphors, divalent europium gives blue phosphors. The two europium phosphor classes, 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 is the phosphor system typically encountered in the helical fluorescent lightbulbs. Combining the same three classes is one way to make trichromatic systems in TV and computer screens. It is also being used as an agent for the manufacture of fluorescent glass. <!--A salt of Europium is a component of the newer phosphorescent powders and paints, some of which will glow for days after a few minutes of exposure to light. PLEASE SEE TALK --> Europium fluorescence is used to interrogate biomolecular interactions in drug-discovery screens. It is also used in the anti-counterfeiting phosphors in [[Euro]] banknotes. <ref> Europium and the Euro [http://www.smarterscience.com/eurosandeuropium.html]</ref> Europium is commonly included in trace element studies in [[geochemistry]] and [[petrology]] to understand the processes that form [[igneous rocks]] (rocks that cooled from [[magma]] or [[lava]]). The nature of the [[europium anomaly]] found is used to help reconstruct the relationships within a suite of igneous rocks. == History == Europium was first found by [[Paul Émile Lecoq de Boisbaudran]] in [[1890]], who obtained basic fraction from [[samarium]]-[[gadolinium]] concentrates which had spectral lines not accounted for by [[samarium]] or [[gadolinium]]; however, the discovery of europium is generally credited to [[France|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 europium in [[1901]]. 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 mad scramble for the limited supply of europium on hand among the monazite processors. (Typical europium content in monazite was about 0.05%.) Luckily, Molycorp, with its [[bastnäsite]] deposit at [[Mountain Pass, California]], whose lanthanides had an unusually "rich" 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 in use in the TV industry ever since, and, of course, also 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, in the 1930s, he was lecturing on the rare earths 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 the Dr. McCoy who had developed a famous method of europium purification involving redox chemistry. == Occurrence == Europium is never found in nature as a free element; however, there are many minerals containing europium, with the most important sources being [[bastnäsite]] and [[monazite]]. Europium has also been identified in the spectra of the sun and certain stars. Depletion or enrichment of europium in minerals relative to other rare earth elements is known as the [[europium anomaly]]. Divalent europium in small amounts happens to be the activator of the bright blue fluorescence of some samples of the mineral fluorite (calcium difluoride). The most outstanding examples of this originated around [[Weardale]], and adjacent parts of northern England, and indeed it was this fluorite that gave its name to the phenomenon of fluorescence, although it was not until much later that europium was discovered or determined to be the cause. == Compounds == Europium compounds include: * [[Fluoride]]s: [[europium(II) fluoride|EuF<sub>2</sub>]] [[europium(III) fluoride|EuF<sub>3</sub>]] * [[Chloride]]s: [[europium(II) chloride|EuCl<sub>2</sub>]] [[europium(III) chloride|EuCl<sub>3</sub>]] * [[Bromide]]s: [[europium(II) bromide|EuBr<sub>2</sub>]] [[europium(III) bromide|EuBr<sub>3</sub>]] * [[Iodide]]s: [[europium(II) iodide|EuI<sub>2</sub>]] [[europium(III) iodide|EuI<sub>3</sub>]] * [[Oxide]]s: [[europium(II) oxide|EuO]] [[europium(III) oxide|Eu<sub>2</sub>O<sub>3</sub>]] Eu<sub>3</sub>O<sub>4</sub> * [[Sulfide]]s: [[europium(II) sulfide|EuS]] * [[Selenide]]s: [[europium(II) selenide|EuSe]] * [[telluride (chemistry)|Telluride]]s: [[europium(II) telluride|EuTe]] * [[Nitride]]s: [[europium(III) nitride|EuN]] Europium(II) compounds tend to predominate, in contrast to most [[Lanthanoid|lanthanide]]s: (which generally form compounds with an oxidation state of +3). Europium(II) chemistry is very similar to [[barium]](II) chemistry, as they have similar [[ionic radius|ionic radii]]. Divalent europium is a mild reducing agent, such that under atmospheric conditions, it is the trivalent form that predominates. Under anaerobic, and particularly under geothermal conditions, the divalent form is sufficiently stable such that it tends to be incorporated into minerals of calcium and the other alkaline earths. This is the cause of the "negative europium anomaly", that depletes europium from being incorporated into the most usual light lanthanide minerals such as monazite, relative to the chondritic abundance. Bastnäsite tends to show less of a negative europium anomaly than monazite does, and hence is the major source of europium today. The accessible divalency of europium has always made it one of the easiest lanthanides to extract and purify, even when present, as it usually is, in low concentration. ''See also [[:Category:Europium compounds|europium compounds]].'' == Isotopes == {{main|Isotopes of europium}} Naturally occurring europium is composed of 2 [[isotope]]s, <sup>151</sup>Eu and <sup>153</sup>Eu, with <sup>153</sup>Eu being the most abundant (52.2% [[natural abundance]]). While <sup>153</sup>Eu is stable, <sup>151</sup>Eu was recently found to be unstable to [[alpha decay]] with [[half-life]] of <math>5_{-3}^{+11}\times 10^{18}</math> yr<ref>Search for α decay of natural Europium, P. Belli, R. Bernabei, F. Cappell, R. Cerulli, C.J. Dai, F.A. Danevich, A. d'Angelo, A. Incicchitti, V.V. Kobychev, S.S. Nagorny, S. Nisi, F. Nozzoli, D. Prosperi, V.I. Tretyak, and S.S. Yurchenko, Nucl. Phys. A '''789''', 15 (2007) {{doi|10.1016/j.nuclphysa.2007.03.001}}</ref>, in reasonable agreement with theoretical predictions. Besides natural radioisotope <sup>151</sup>Eu, 35 artificial radioisotopes have been characterized, with the most stable being <sup>150</sup>Eu with a [[half-life]] of 36.9 years, <sup>152</sup>Eu with a half-life of 13.516 years, and <sup>154</sup>Eu with a half-life of 8.593 years. All of the remaining [[radioactive]] isotopes have half-lives that are less than 4.7612 years, and the majority of these have half-lives that are less than 12.2 seconds. This element also has 8 [[meta state]]s, with the most stable being <sup>150m</sup>Eu (t<sub>½</sub> 12.8 hours), <sup>152m1</sup>Eu (t<sub>½</sub> 9.3116 hours) and <sup>152m2</sup>Eu (t<sub>½</sub> 96 minutes). The primary [[decay mode]] before the most abundant stable isotope, <sup>153</sup>Eu, is [[electron capture]], and the primary mode after is [[beta minus decay]]. The primary [[decay product]]s before <sup>153</sup>Eu are isotopes of [[samarium]] (Sm) and the primary products after are isotopes of [[gadolinium]] (Gd). == Europium as a nuclear fission product == {| class="wikitable" align="right" |+ Thermal neutron capture cross sections !Isotope |<sup>151</sup>Eu||<sup>152</sup>Eu||<sup>153</sup>Eu||<sup>154</sup>Eu||<sup>155</sup>Eu |- !Yield |~10||low||1580||>2.5||330 |- !Barns |5900||12800||312||1340||3950 |} {{Medium-lived fission products}} Europium is produced by nuclear fission, but the [[fission product yield]]s of europium isotopes are low near the top of the mass range for [[fission products]]. Like other [[Lanthanoid|lanthanides]], many isotopes, especially isotopes with odd mass numbers and neutron-poor isotopes like <sup>152</sup>Eu, have high [[cross section]]s for [[neutron capture]], often high enough to be [[neutron poison]]s. <sup>151</sup>Eu is the [[beta decay]] product of [[Sm-151]], but since this has a long decay half-life and short mean time to neutron absorption, most <sup>151</sup>Sm instead winds up as <sup>152</sup>Sm. <sup>152</sup>Eu (half-life 13.516 years) and <sup>154</sup>Eu (halflife 8.593 years) cannot be beta decay products because <sup>152</sup>Sm and <sup>154</sup>Sm are nonradioactive, but <sup>154</sup>Eu is the only long-lived "shielded" [[nuclide]], other than [[Cs-134|<sup>134</sup>Cs]], to have a fission yield of more than 2.5 [[parts per million]] fissions.<ref>ORNL Table of the Nuclides</ref> A larger amount of <sup>154</sup>Eu will be produced by [[neutron activation]] of a significant portion of the nonradioactive<sup>153</sup>Eu; however, much of this will be further converted to <sup>155</sup>Eu. [[Eu-155|<sup>155</sup>Eu]] (halflife 4.7612 years) has a fission yield of 330 ppm for [[U-235]] and [[thermal neutron]]s. Most will be transmuted to nonradioactive and nonabsorptive [[Gadolinium]]-156 by the end of fuel [[burnup]]. Overall, europium is overshadowed by [[Cs-137]] and [[Sr-90]] as a radiation hazard, and by [[samarium]] and others as a neutron poison. == Precautions == The toxicity of europium compounds has not been fully investigated, but there are no clear indications that europium is highly toxic compared to other heavy metals. The metal dust presents a fire and explosion hazard. Europium has no known biological role. == Isolation of Europium == Europium metal is available commercially, so it is not normally necessary to make it in the laboratory — which is just as well, as it is difficult to isolate as the pure metal. This is largely because of the way it is found in nature, wherein the lanthanoids are found in a number of minerals. The most important are [[xenotime]], [[monazite]], and [[bastnäsite]]. The first two are orthophosphate minerals LnPO<sub>4</sub> (Ln denotes a mixture of all the lanthanoids except [[promethium]] which is vanishingly rare due to being radioactive) and the third is a fluoride carbonate LnCO<sub>3</sub>F. Lanthanoids with even atomic numbers are more common. The most common lanthanoids in these minerals are, in order, [[cerium]], [[lanthanum]], [[neodymium]], and [[praseodymium]]. Monazite also contains [[thorium]] and [[yttrium]], which makes handling difficult since thorium and its decomposition products are radioactive. For many purposes it is not particularly necessary to separate the metals, but if separation into individual metals is required, the process is complex. Initially, the metals are extracted as salts from the ores by extraction with [[sulfuric acid]] (H<sub>2</sub>SO<sub>4</sub>), [[hydrochloric acid]] (HCl), and [[sodium hydroxide]] (NaOH). Modern purification techniques for these lanthanoid salt mixtures are ingenious and involve selective [[complexation]] techniques, [[solvent extraction]]s, and [[ion exchange chromatography]]. Pure europium is available through the electrolysis of a mixture of molten EuCl<sub>3</sub> and NaCl (or CaCl<sub>2</sub>) in a graphite cell which acts as cathode, using graphite as anode. The other product is [[chlorine]] gas. == Footnotes == <references/> == References == *[http://periodic.lanl.gov/elements/63.html Los Alamos National Laboratory &ndash; Europium] == External links == {{Commons|Europium}} {{wiktionary|europium}} * [http://www.webelements.com/webelements/elements/text/Eu/index.html WebElements.com &ndash; Europium] * [http://education.jlab.org/itselemental/ele063.html It's Elemental &ndash; Europium] {{clear}} {{Compact periodic table}} [[Category:Chemical elements]] [[Category:Lanthanides]] <!-- interwiki --> [[af:Europium]] [[ar:يوروبيوم]] [[bn:ইউরোপিয়াম]] [[be:Еўропій]] [[bs:Europijum]] [[ca:Europi]] [[cs:Europium]] [[co:Europiu]] [[da:Europium]] [[de:Europium]] [[et:Euroopium]] [[el:Ευρώπιο]] [[es:Europio]] [[eo:Eŭropio]] [[eu:Europio]] [[fa:یوروپیوم]] [[fr:Europium]] [[fur:Europi]] [[gv:Oarpium]] [[gl:Europio]] [[ko:유로퓸]] [[hy:Եվրոպիում]] [[hr:Europij]] [[io:Europio]] [[id:Europium]] [[it:Europio]] [[he:אירופיום]] [[jv:Europium]] [[ht:Ewòpyòm]] [[la:Europium]] [[lv:Eiropijs]] [[lb:Europium]] [[lt:Europis]] [[jbo:ronjinme]] [[hu:Európium]] [[ml:യൂറോപ്പിയം]] [[nl:Europium]] [[ja:ユウロピウム]] [[no:Europium]] [[nn:Europium]] [[pl:Europ]] [[pt:Európio]] [[ro:Europiu]] [[ru:Европий]] [[scn:Europiu]] [[sk:Európium]] [[sl:Evropij]] [[sr:Еуропијум]] [[sh:Europijum]] [[stq:Europium]] [[fi:Europium]] [[sv:Europium]] [[ta:யூரோப்பியம்]] [[th:ยูโรเพียม]] [[tg:Европий]] [[tr:Evropiyum]] [[uk:Європій]] [[zh:铕]]