Heat Capacities of Lanthanide Compounds, Their Morphology Schottky, and Lattice Contribution

Abstract

With gradual accumulation of precise cryogenic calorimetric data on the sesquioxides, chalcogenides (notably the sesquisulfides), hexaborides, hydrides, pnictides, halides, and especially the tri-hydroxides, an appreciation of the important contribution made by Schottky heat capacity contributions has arisen. In an attempt to understand and analyze — and ultimately to correlate and to predict the morphology and thermophysics of heat capacity of transition element binary compounds — increasing attention is focussed on the lattice heat capacity contribution. Accurate knowledge of the lattice contribution is essential in the resolution of electronic, magnetic, Schottky and other contributions to the heat capacity. The importance of correlating the lattice contribution with molal volumes of the compounds as well as with cation masses (of lanthanide cations) will be discussed — in the light of recent developments — particularly in lanthanide halides and trihydroxides. The relevance of these developments to other compounds is emphasized.