Comments on the formation thermodynamics of selected groups of rare earth compounds

In the framework of a description of the general alloying behaviour of the rare earth (R) metals, their reaction thermochemistry is reviewed. Problems met in the thermochemical characterization and in the experimental investi gation of R alloys and compounds are highlighted and discussed. A short sum mary of the work in this field, carried out in our laboratory is reported. Special attention is given to the work performed and in progress on selecte d groups of R compounds: these are aurides, arsenides, antimonides, bismuth ides and tellurides. The results obtained in the standard enthalpy measurem ents by direct calorimetry for RAu compounds, La-As, Tb-Bi and Ce-Te solid alloys are reported and discussed. Typical values of Delta H-f degrees (kJ/ mol at. at 300 K) are: LaAu, -72.0 +/-2.0; Ce2Au, -55.0 +/-1.0: GdAu, -82.0 +/-2.0: TbAu, -82.0 +/-2.0: DyAu, -82.0 +/-3.0: HoAu. -83.0 +/-4.0; YbAu, -75.0 +/-2.0, LaAs, -150.0 +/-3.0, TbBi, -104.0 +/-2.0: CeTe. -168 +/-4 and Ce3Te4-Ce2Te3, -163 +/-4. (C) 2001 Elsevier Science B.V. All rights reserv ed.