Yttrium ceramic material

The alkoxides and aryloxides, particularly of yttrium have excited recent interest. This is because of their potential use in the production of electronic and ceramic materials,in particular high temperature superconductors, by the deposition of pure oxides (metallo-organic chemical vapour deposition, MOCVD). They are moisture sensitive but mostly polymeric and involatile and so attempts have been made to inhibit polymerization and produce the required volatility by using bulky alkoxide ligands. M(OR)3, R = 2,6-di-terr-butyl-4-methylphenoxide, are indeed 3-coordinate (pyramidal) monomers but still not sufficiently volatile. More success has been achieved with fluorinated alkoxides, prepared by reacting the parent alcohols with the metal tris-(bis-trimethylsilylamides) ... 

Unlike the PEM, the ionic conduction occurs for the oxygen ion instead of the hydrogen ion. SOFCs are made of ceramic materials like zirconium (Z = 40) stabilized by yttrium (Z = 39). High-temperature oxygen conductivity is achieved by creating oxygen vacancies in the lattice structure of the electrolyte material. The halfcell reactions in this case are... 

Baddeleyite has a monocHnic structure with space group Plljc. The Zr + ion has seven-fold coordination, while the idealized ZrOz polyhedron is close to tetrahedral orientation, where one angle in the structure is different significantly from the tetrahedral value. Natural baddeleyite is a raw material for zirconium. In industry ZrOz, named usually zirconia, is important in areas such as surface chemistry, where its activity as a red ox material and its acid-based functions are important. As a ceramic material, zirconia can resist very high temperatures and its stabihzed form, yttrium-stabihzed zirconiiun, shows remarkable mechanical properties. 

Research chemists found that they could modify the conducting properties of solids by doping them, a process commonly used to control the properties of semiconductors (see Section 3.13). In 1986, a record-high Ts of 35 K was observed, surprisingly not for a metal, but for a ceramic material (Section 14.24), a lanthanum-copper oxide doped with barium. Then early in 1987, a new record T, of 93 K was set with yttrium-barium-copper and a series of related oxides. In 1988, two more oxide series of bismuth-strontium-calcium-copper and thallium-barium-calcium-copper exhibited transition temperatures of 110 and 125 K, respectively. These temperatures can be reached by cooling the materials with liquid nitrogen, which costs only about 0.20 per liter. Suddenly, superconducting devices became economically viable. 

S. L. Wu, H. P. Li et al.. Sol-gel preparation and characteristic on ultrafme BaTiOj and Semiconducting BaTiOj Ceramics doped with yttrium, Functional Material, 26(1995) pp. 427-430. 

Yttrium is also a deoxidizer of vanadium, and its addition improves the ductility of nodular cast iron. Yttrium oxides increase the resistance of ceramic materials to heating due to an increase in melting temperature. Yttrium hydrate is used as temperature stabilizer both to increase the stability of heating alloys and to moderate neutrons in nuclear reactors (Luckey and Venugopal 1978 Greinacher 1981 Jezowska-Trzebia-towska et al. 1990). 

R.A. Lefever, J. Matsko, Transparent yttrium oxide ceramics, Materials Research Bulletin, 2, 865-9 (1967). 

Ferrite A ceramic material made of powdered and compressed ferric oxide, plus other oxides (mainly cobalt, nickel, zinc, yttrium-iron, and manganese). These materials have low eddy current losses at high frequencies. 

High-temperature superconducting materials have been made using some of the transition elements. In particular, a ceramic material that is superconducting at 92 K is made from yttrium, barium, copper, and oxygen. These ceramic materials have the potential for many applications, for example, more efficient electric power transmission. 

Electrical and Electronic Applications. Silver neodecanoate [62804-19-7] has been used in the preparation of a capacitor-end termination composition (110), lead and stannous neodecanoate have been used in circuit-board fabrication (111), and stannous neodecanoate has been used to form patterned semiconductive tin oxide films (112). The silver salt has also been used in the preparation of ceramic superconductors (113). Neodecanoate salts of barium, copper, yttrium, and europium have been used to prepare superconducting films and patterned thin-fHm superconductors. To prepare these materials, the metal salts are deposited on a substrate, then decomposed by heat to give the thin film (114—116) or by a focused beam (electron, ion, or laser) to give the patterned thin film (117,118). The resulting films exhibit superconductivity above Hquid nitrogen temperatures. 

The key to the superconducting properties of these ceramics seems to be the presence of planes of copper and oxygen atoms bonded to one another. The significance of the other atoms in the lattice seems to be to provide a stmctural framework for the copper and oxygen atoms. Thus, in the superconducting compound YBa2Cu30, the substitution of other rare earths for yttrium resrrlts in little change in the properties of the material. 

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