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Yttria can serve as host lattice for doping with Eu3+ cations as well as reactant to gain doped yttrium orthovanadate YVO4:Eu3+ or yttrium oxide sulfide :Eu3+ phosphors that give the red color in color television picture tubes, though the red color itself is actually emitted from the europium while the yttrium collects energy from the electron gun and passes it to the phosphor. Yttrium compounds can serve as host lattices for doping with different lanthanoid cations. Besides Eu3+ also Tb3+ can be used as a doping agent leading to green luminescence. Yttria is also used as a sintering additive in the production of porous silicon nitride and as a common starting material for both material science and for producing other compounds of yttrium.Yttrium compounds are used as a catalyst for ethylene polymerization. As a metal, it is used on the electrodes of some high-performance spark plugs. Yttrium is also used in the manufacturing of gas mantles for propane lanterns as a replacement for thorium, which is radioactive.
Developing uses include yttrium-stabilized zirconia in particular as a solid electrolyte and as an oxygen sensor in automobile exhaust systems.
Garnets
Yttrium is used in the production of a large variety of synthetic garnets, and yttria is used to make yttrium iron garnets ( or YIG), which are very effective microwave filters. Yttrium, iron, aluminium, and gadolinium garnets (e.g. Y3(Fe,Al)5O12 and Y3(Fe,Ga)5O12) have important magnetic properties. YIG is also very efficient as an acoustic energy transmitter and transducer. Yttrium aluminium garnet ( or YAG) has a hardness of 8.5 and is also used as a gemstone in jewelry (simulated diamond). Cerium-doped yttrium aluminium garnet (YAG:Ce) crystals are used as phosphors to make white LEDs.YAG, yttria, yttrium lithium fluoride , and yttrium orthovanadate 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 used for drilling into and cutting metal. The single crystals of doped YAG are normally produced by the Czochralski process.
Material enhancer
Small amounts of yttrium (0.1 to 0.2%) have been used to reduce the grain sizes of chromium, molybdenum, titanium, and zirconium. It is also used to increase the strength of aluminium and magnesium alloys. The addition of yttrium to alloys generally improves workability, adds resistance to high-temperature recrystallization and significantly enhances resistance to high-temperature oxidation (see graphite nodule discussion below).Yttrium can be used to deoxidize vanadium and other non-ferrous metals. Yttria is used to stabilize the cubic form of zirconia for use in jewelry.
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 lenses.
Medical
The radioactive isotope yttrium-90 is used in drugs such as Yttrium Y 90-DOTA-tyr3-octreotide and Yttrium Y 90 ibritumomab tiuxetan for the 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 can cut more precisely than scalpels, have been used to sever pain-transmitting nerves in the spinal cord, and yttrium-90 is also used to carry out radionuclide synovectomy in the treatment of inflamed joints, especially knees, in sufferers of conditions such as rheumatoid arthritis.
A neodymium-doped yttrium-aluminium-garnet laser has been used in an experimental, robot-assisted radical prostatectomy in canines in an attempt to reduce collateral nerve and tissue damage, whilst the erbium-doped ones are starting to be used in cosmetic skin resurfacing.
Superconductors
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 (77.1& K). As the price of liquid nitrogen is lower than that of liquid helium, which has to be used for the metallic superconductors, the operating costs would decrease.The actual superconducting material is often written as YBa2Cu3O7–''d'', where ''d'' must be less than 0.7 if the material is to be superconducting. The reason for this is still not clear, but it is known that the vacancies occur only in certain places in the crystal, the copper oxide planes and chains, giving rise to a peculiar oxidation state of the copper atoms, which somehow leads to the superconducting behavior.
The theory of low temperature superconductivity has been well understood since the so-called BCS theory was put forward in 1957. It is based on a peculiarity of the interaction between 2 electrons in a crystal lattice. However, BCS theory does not explain high temperature superconductivity, and its precise mechanism is still a mystery. What is known is that the composition of the copper-oxide materials has to be precisely controlled if superconductivity is to occur.
The created material was a black and green, multi-crystal, multi-phase mineral. Researchers are studying a class of materials known as perovskites that are alternative mixtures of these elements, hoping to eventually develop a practical high-temperature superconductor.
Adapted from the Wikipedia article Yttrium, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki
