A LANTHANIDE LANTHOLOGY (.pdf) - Davidson Physics

YTTRIUMIt forms aqueous-insoluble oxides, oxalates, hydroxides, carbonates and phosphates aswell as soluble nitrates and chlorides. The sulfates and acetates are more soluble for Y and theheavies than for the light lanthanides. In comparison to lanthanum, the carbonate and oxalate tendto be solubilized in the presence of excess anion, presumably stable species such as Y(C 2 O 4 ) n - exist.Double salts also tend to be more soluble for Y and the heavies than for La and the lights.The element Y has an exceptionally high thermo-dynamic affinity for oxygen, free energy offormation 1817 kJmol -1 , probably the greatest of any element.[3] The property underlies many ofyttrium's uses not only as the yttrium oxide but also as the metal. Yttrium is the active componentin the MCrAlY family of alloys used in high temperature oxidizing environments. The trace of Ypresent enhances the stability of the alumina/chromia oxide coating by improving resistance tospalling. It has been suggested that yttrium "getters" sulfur at the oxide crystallite interfaces[4]. Thegettering effect of Yttrium has also been used in discharge lamps[5]. The affinity for hydrogen canprovide a chemical-trap method for removing trace amounts of hydrogen from molten alkali metalcircuits in certain nuclear reactors.The superconducting properties of the Y-Ba-Cu-0 system have led to an immense amount ofresearch and associated publications. A variety of processes for the preparation of these and similarmaterials are now known. Many properties, in addition to superconductivity-related behavior, havebeen investigated. Yttrium’s chemical and physical behavior in many compounds is now betterunderstood and may well lead to other uses in addition to ceramic superconductors.[3] Thermochemistry of the Rare Earths, Part I Rare Earth Oxides etc., K.A.Gschneidner et al., ReportIS-RIC-6, publ. Rare Earth Information Center, Iowa State University, Ames Iowa, 1973 (available fromMolycorp)[4] A Relationship between Indigenous Impurity Elements and Protective Oxide Scale Adherence, J.G.Smeggilet al., Metall[.Trans.A, 1986, 17A, 923[5] A Getter for Metal-Iodide High Pressure Mercury Vapour Lamps, G.Kuus, Philips Tech.Rev., 1975,35(11),35454