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Yttrium (Template:PronEng), is a chemical element that has the symbol Y and atomic number 39. A silvery metallic transition metal, yttrium is common in rare-earth minerals and two of its compounds are used to make the red color phosphors in cathode ray tube displays, such as those used for televisions.

Yttrium was first isolated in 1828 by Friedrich Wöhler. Yttrium's only stable isotope, Y is also its only naturally occurring isotope. Yttrium has no known biological role, and exposure to yttrium compounds can cause lung disease in humans.

Characteristics

Yttrium is a soft silver-metallic, lustrous transition metal that is chemically similar to and always found with the rare earth elements. It chemically resembles the rare earth elements more closely than its neighbor in the periodic table, scandium and if its physical properties were plotted against atomic number, then it would have an apparent number of 64.5 to 67.5, placing it between gadolinium and erbium (yttrium often also falls in the same range for reaction order). One of the few notable differences in the chemistry of yttrium with the rare earths is the fact that only a trivalent state is known, whereas around half of the rare earths have valences other than their normal value of three.

The element forms an insoluble fluoride,hydroxide, and oxalate in aqueous solution but its bromide, chloride, iodide, nitrate and sulfate are all soluble in water. Y ions are colorless in solution because of the absence of d and f electron shells and their size in solution is so close to heavy rare earths that it behaves as if it were one of them.

In bulk form, it is relatively stable in air due to the formation of a protective oxide film on its surface. When heated to 750 °C in water vapor a protective film 10 Å thick is formed. But when yttrium is finely divided it is very unstable in air; shavings or turnings of the metal can ignite in air at temperatures exceeding 400 °C. Yttrium nitride (YN) is formed when the metal is heated to 1000 °C in nitrogen.

Concentrated nitric and hydrofluoric acids do not rapidly attack yttrium but other acids do. Halogens form trihalides with yttrium at temperatures above around 200 °C and carbon, phosphorous, selenium, silicon and sulfur all form binary compounds with yttrium at elevated temperatures. The carbides Y₃C, Y₂C, and YC₂ can each hydrolyze to form hydrocarbons.

The metal has a low neutron cross-section for nuclear capture. Water attacks the element and is decomposed by it into hydrogen gas.

Yttrium chemically resembles the lanthanides, and can appear to gain a slight pink luster on exposure to light. The common oxidation state of yttrium is +3.

Applications

Consumer

Yttrium(III) oxide is the most important yttrium compound and is widely used to make YV O₄:Eu and Y₂O₃:Eu phosphors that give the red color in color television picture tubes. The red color actually is emitted from the europium while the yttrium collects energy from the electron gun and passes it to the phosphor.

Yttria (yttrium(III) oxide) is used as a sintering additive in the production of porous silicon nitride. Yttrium is used as a catalyst for ethylene polymerization. It is used on the electrodes of some high-performance spark plugs. Yttrium is also used in the manufacture of gas mantles for propane lanterns, as a replacement for thorium, which is slightly radioactive.

Garnets

Yttrium oxide is also used to make yttrium iron garnets (YIG) which are very effective microwave filters. Yttrium iron, aluminium, and gadolinium garnets (e.g. Y₃Fe₅O₁₂ and Y₃Al₅O₁₂) have important magnetic properties. YIG is also very efficient as an acoustic energy transmitter and transducer.

Yttrium aluminium garnet (YAG) has a hardness of 8.5 and is also used as a gemstone (simulated diamond). Cerium-doped yttrium aluminium garnet (YAG:Ce) crystals are used as phosphors to make white LEDs.

YAG, Y₂O₃, yttrium lithium fluoride, and yttrium vanadate are used in combination with dopants such as neodymium, erbium, ytterbium in near-infrared lasers. YAG lasers have the ability to operate at high power and are particularly good drilling into and cutting metal.

Material enhancer

Small amounts of the element (0.1 to 0.2%) have been used to reduce grain size of chromium, molybdenum, titanium, and zirconium. It is also used to increase the strength of aluminium and magnesium alloys. The addition of yttrium in alloys generally improves workability, adds resistance to high-temperature recrystallization and significantly enhances resistance to high-temperature oxidation (see graphite nodule discussion below).

It can be used to deoxidize vanadium and other non-ferrous metals. Yttrium oxide is used to stabilize the cubic form of zirconia, for use in jewelry, etc.

Yttrium has been studied for possible use as a nodulizer in the making of nodular cast iron which has increased ductility (the graphite forms compact nodules instead of flakes to form nodular cast iron). Yttrium oxide can also be used in ceramic and glass formulas, since it has a high melting point and imparts shock resistance and low thermal expansion characteristics. It is therefore used in camera lens.

Medical and exotic

The radioactive isotope yttrium-90 is used for treatment of various cancers, including lymphoma, leukemia, ovarian, colorectal, pancreatic, and bone cancers. It works by adhering to monoclonal antibodies, which in turn bind to cancer cells and kill them via intense β-radiation from the yttrium-90 (see Monoclonal antibody therapy). Needles made of yttrium-90, which cut more precisely than a scalpel, have also been used to sever pain-transmitting nerves in the spinal cord.

A neodymium-doped yttrium-aluminium-garnet laser was used in an experimental robotically assisted radical prostatectomy in canines in an attempt to reduce collateral nerve and tissue damage.

Yttrium was used in the yttrium barium copper oxide (YBa₂Cu₃O₇, aka 'YBCO' or '1-2-3') superconductor developed at the University of Alabama and the University of Houston in 1987. This superconductor operated at 93 K, notable because this is above liquid nitrogen's boiling point (77.1K). The matter created was a multi-crystal multi-phase mineral, which was black and green. Researchers are studying a class of materials called perovskites that are alternate mixtures of these elements, hoping to eventually develop a practical high-temperature superconductor.

History

In 1787, army lieutenant and part-time chemist Karl Axel Arrhenius found a heavy black rock in an old quarry near the Swedish village of Ytterby (now part of the Stockholm Archipelago). Thinking that it was an unknown mineral containing the newly-discovered element tungsten, he named it ytterbite (after the village plus the -ite ending to indicate it was a mineral) and sent samples to various chemists for further analysis.

Johan Gadolin at the University of Åbo identified a new oxide or 'earth' in Arrhenius' sample in 1789 and published his completed analysis in 1794. Anders Gustaf Ekeberg confirmed this in 1797 and named the new oxide yttria, meaning that the new element would be named yttrium.

Carl Gustav Mosander found in 1843 that samples of yttria had traces of three oxides: yttria (white yttrium oxide), erbia (yellow terbium oxide) and the rose-colored terbia (erbium oxide). A fourth oxide, ytterbium oxide, was isolated in 1878 by Jean Charles Galissard de Marignac. New elements would later be isolated from each of those oxides and each element was named, in some fashion, after Ytterby, the village near the query in which they were found (see ytterbium, terbium, and erbium). Since yttria was a mineral after all and not an oxide, Martin Heinrich Klaproth renamed it in honor of Gadolin and gave it an -ite ending to indicate this; gadolinite.

Yttrium metal was first isolated in 1828 when Friedrich Wöhler heated anhydrous yttrium chloride with potassium metal.

YCl₃ + K -> 2KCl + Y

Occurrence

Geological

This element is found in almost all rare earth minerals and in uranium ores but is never found in nature as a free element. About 30 ppm of the Earth's crust is yttrium, making it the 28th most abundant element there and 400 times more common than silver. It is found in soil in concentrations that range from 10 to 150 ppm (dry weight average of 23 ppm) and in sea water at 9 ppt. Lunar rock samples from the Apollo program have a relatively high yttrium content.

Yttrium is primarily recovered from monazite ) sand, which contains 3% of the element and bastnasite (), which contains 0.2% yttrium. Yttrium is also found in samarskite, a yellow-brown ore mined in Malaysia called xenotime which has up to 50% yttrium phosphate (YPO₃) and a black glassy ore found in Madagascar called fergusonite.

It is difficult to separate from other rare earths and when extracted, is a dark gray powder. Annual world production of yttrium oxide was 600 tonnes by 2001 with reserves estimated at 9 million tonnes. Only a few tonnes of yttrium metal are produced each year by reducing yttrium fluoride with calcium metal.

Due to the lanthanide contraction, ytrrium, which is trivalent, is of similar ionic size to dysprosium and its lanthanide neighbors. Due to the relatively gradual decrease in ionic size with increasing atomic number, the rare earth elements have always been difficult to separate. Even with eons of geological time, geochemical separation of the lanthanides has only rarely progressed much farther than a broad separation between light versus heavy lanthanides, otherwise known as the cerium and yttrium earths. This geochemical divide is reflected in the first two rare earths that were discovered, yttria in 1794 and ceria in 1803. As originally found, each comprised the entire mixture of the associated earths. Rare earth minerals, as found, usually are dominated by one group or the other, depending upon which size-range best fits the structural lattice. Thus, among the anhydrous rare earth phosphates, it is the tetragonal mineral xenotime that incorporates yttrium and the yttrium earths, whereas the monoclinic monazite phase incorporates cerium and the cerium earths preferentially. The smaller size of the yttrium group allows it a greater solid solubility in the rock-forming minerals that comprise the earth's mantle, and thus yttrium and the yttrium earths show less enrichment in the earth's crust, relative to chondritic abundance, than does cerium and the cerium earths. This has economic consequences: large orebodies of the cerium earths are known around the world, and are being actively exploited. Corresponding orebodies for yttrium tend to be rarer, smaller, and less concentrated. Most of the current supply of yttrium originates in the "ion adsorption clay" ores of Southern China. Some versions of these provide concentrates containing about 65% yttrium oxide, with the heavy lanthanides being present in ratios reflecting the Oddo-Harkins rule: even-numbered heavy lanthanides at abundances of about 5% each, and odd-numbered lanthanides at abundances of about 1% each. Similar compositions are found in xenotime or gadolinite.

Well-known minerals that contain yttrium include gadolinite, xenotime, samarskite, euxenite, fergusonite, yttrotantalite, yttrotungstite, yttrofluorite (a variety of fluorite), thalenite, yttrialite. Small amounts occur in zircon, which derives its typical yellow fluorescence from some of the accompanying heavy lanthanides. The zirconium mineral eudialyte, such as is found in southern Greenland, also contains small but potentially useful amounts of yttrium. Of the above yttrium minerals, most played a part in providing research quantities of lanthanides during the discovery days. Xenotime is occasionally recovered as a byproduct of heavy sand processing, but has never been nearly as abundant as the similarly recovered monazite (which typically contains a few percent of yttrium). Uranium ores processed in Ontario have occasionally yielded yttrium as a byproduct.

Biological

Yttrium has no known biological role, though it is found in most, if not all, organisms and tends to concentrate in the liver and bones of humans. There is normally as little as 0.5 milligrams found within the entire human body and human breast milk contains 4 ppm. Yttrium can be found in edible plants in concentrations between 20 ppm and 100 ppm (fresh weight), with cabbage having the largest amount. With up to 700 ppm, the seeds of woody plants have the highest known concentrations.

Isotopes

Y is both the only stable isotope and the only naturally occurring isotope of yttrium. 32 artificial isotopes have been synthesized, ranging in atomic mass from 76 to 108. The least stable of these is Y with a half-life of 500 ns, and the most stable is Y with a half-life of 106.65 days. Yttrium isotopes with masses at or below 88 decay primarily by positron emission, while those with masses at or above 90 decay primarily by electron emission. Isotopes with masses at or above 97 are also known to have minor decay paths of β− delayed neutron emission.

Yttrium has at least 25 metastable isomers ranging in atomic mass from 78 to 102. Within this range, only Y, Y, Y, Y, Y, and Y do not have isomers. Multiple excitation states have been observed for Y, Y, Y, Y, and Y. While most of yttrium's isomers are expectedly less stable than their ground state, Y, Y, Y, Y, Y, Y, and Y have longer half-lives than their ground states, as these isomers decay by beta decay rather than isomeric transition.

Y exists in equilibrium with its parent isotope strontium-90 (Sr), which is a product of nuclear explosions and a waste product of nuclear reactors. Sr has a half-life of 29 years while Y has a half-life of 64 hours. Complete extraction of Y from Sr is important prior to many medical uses due to the fact that Sr behaves similar to calcium in the body and can therefore cause bone cancer.

Precautions

Water soluble compounds of yttrium are considered mildly-toxic, while its insoluble compounds are non-toxic. In experimental animals, yttrium and its compounds caused lung and liver damage, though toxicity varies with different yttrium compounds. In rats, inhalation of yttrium citrate caused pulmonary edema and dyspnea, and inhalation of yttrium chloride caused liver edema, pleural effusions, and pulmonary hyperemia.

Exposure to yttrium compounds in humans can cause lung disease. Workers exposed to airborne yttrium europium vanadate dust experienced mild eye, skin, and upper respiratory tract irritation, though this may have been caused by the vanadium content rather than the yttrium. Acute exposure to yttrium compounds can cause shortness of breath, coughing, chest pain, and cyanosis. NIOSH recommends a time weighted average limit of 1 mg/m and an IDLH of 500 mg/m.

Notes

Sound file - pronunciation
^ Emsley 2001, p.498
Daane 1968, p.810
Daane 1968, p.815
^ Daane 1968, p.817
^ Husted 2003, "yttrium"
^ Lide 2008, v.4,p.41
Emsley 2001, p.497 says that "Yttrium oxysulfide, doped with europium, is used as the standard red component in colour televisions".
^ Daane 1968, p.818
Addison 1985
Kong et. al. 2005
Tokurakawa et. al. 2007
^ Stwertka 1998, p.116
^ Emsley 2001, p.497
^ Emsley 2001, p.495
^ Emsley 2001, p.496 Cite error: The named reference "Emsley496" was defined multiple times with different content (see the help page).
Kaouk, Jihad H. (September 2008). "Laser robotically assisted nerve-sparing radical prostatectomy: a pilot study of technical feasibility in the canine model". BJU International. 102 (5). Cleveland: Glickman Urological Institute: 598(5). doi:http://dx.doi.org/10.1111/j.1464-410X.2008.07708.x. Retrieved 2008-08-04. {{cite journal}}: Check |doi= value (help); External link in |doi= (help)
^ van der Krogt 2005
Stwertka 1998, p.115 says that the identification occurred in 1789 but is silent on when the announcement was made. van der Krogt 2005 cites the original publication, with the year 1794, by Gadolin.
Oxides are given an -a ending and new elements are normally given an -ium ending
Confusingly, the names 'erbia' and 'terbia' were later swapped (van der Krogt 2005). The chemical names given in parenthesis indicate the compound Mosander actually discovered.
Britannica 2005, "ytterbium"
^ Stwertka 1998, p.115
Heiserman 1992, p.150
Emsley 2001, p.497 gives 2.5% for the yttrium content of monazite
^ Audi, G. (2003). "Nubase2003 Evaluation of Nuclear and Decay Properties". Nuclear Physics A. 729. Atomic Mass Data Center: 3–128. doi:10.1016/j.nuclphysa.2003.11.001.
^ "Occupational Safety and Health Guideline for Yttrium and Compounds". United States Occupational Safety and Health Administration. 2007-01-11. Retrieved 2008-08-03.
"Yttrium". NIOSH Pocket Guide to Chemical Hazards. National Institute for Occupational Safety and Health. September 2005. Retrieved 2008-08-03.

References

Addison, Gilbert J. (1985-08-06). "Yttrium oxide mantles for fuel-burning lanterns". Application for U.S. patent. Wichita, KS: The Coleman Company, Inc. US4533317.
Britannica contributors (2005). Encyclopaedia Britannica. Encyclopædia Britannica, Inc. {{cite book}}: |author= has generic name (help)
Daane, A. H. (1968). "Yttrium". In Hampel, Clifford A. (ed.). The Encyclopedia of the Chemical Elements. New York: Reinhold Book Corporation. pp. 810–821. LCCN 68-29938. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
Emsley, John (2001). "Yttrium". Nature's Building Blocks: An A-Z Guide to the Elements. Oxford, England, UK: Oxford University Press. pp. 495–498. ISBN 0198503407.
Heiserman, David L. "Element 39: Yttrium". Exploring Chemical Elements and their Compounds. TAB Books. pp. 150–152. ISBN 0-8306-3018-X. {{cite book}}: Unknown parameter |Location= ignored (|location= suggested) (help)
Husted, Robert (2003-12-15). "Yttrium". Periodic Table of the Elements. Los Alamos National Laboratory. Retrieved 2008-08-02.
J. Kong (2005). "9.2-W diode-pumped Yb:Y₂O₃ ceramic laser". Applied Physics Letters. 86: 116. doi:10.1063/1.1914958. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
van der Krogt, Peter (2005-05-05). "Yttrium". Elementymology & Elements Multidict. Retrieved 2008-08-06.
Lide, David R., ed. (2007–2008), "Zirconium", CRC Handbook of Chemistry and Physics, vol. 4, New York: CRC Press, p. 41, 978-0-8493-0488-0
Stwertka, Albert (1998). "Yttrium". Guide to the Elements (Revised Edition ed.). Oxford University Press. pp. 115–116. ISBN 0-19-508083-1. {{cite book}}: |edition= has extra text (help)
M. Tokurakawa (2007). "Diode-pumped 188 fs mode-locked Yb:Y₂O₃ ceramic laser". Appl.Phys.Lett. 90: 071101. doi:10.1063/1.2476385. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

External links

Periodic table

	1	2															3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
1	H																															He
2	Li	Be																									B	C	N	O	F	Ne
3	Na	Mg																									Al	Si	P	S	Cl	Ar
4	K	Ca															Sc	Ti	V	Cr	Mn	Fe	Co	Ni	Cu	Zn	Ga	Ge	As	Se	Br	Kr
5	Rb	Sr															Y	Zr	Nb	Mo	Tc	Ru	Rh	Pd	Ag	Cd	In	Sn	Sb	Te	I	Xe
6	Cs	Ba	La	Ce	Pr	Nd	Pm	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu	Hf	Ta	W	Re	Os	Ir	Pt	Au	Hg	Tl	Pb	Bi	Po	At	Rn
7	Fr	Ra	Ac	Th	Pa	U	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr	Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Nh	Fl	Mc	Lv	Ts	Og