Tellurium‐Cerium Oxides

Abstract

Abstract Phase equilibria in the (Ce, Te) O system, originating from interaction between Ce(NO 3 ) 3 · 6 H 2 O and H 6 TeO 6 followed by calcination up to 700°C, have been studied by methods of physico‐chemical analysis (DTA, TGA, x‐ray diffraction, XPS). Evidence is given for the formation of non‐stoichiometric fluorite‐type mixed‐crystals (Ce, Te)O 2 in the 450–500°C range, up to a tellurium solubility limit corresponding to a lattice parameter of 5.666(3) Å. At higher temperatures (500–600°C) Ce 2 (TeO 4 ) 3 is stable and Ce(TeO 3 ) 2 is formed above about 550°C. Ce(TeO 3 ) 2 is also obtained by solid‐state interaction between CeO 2 and TeO 2 and is identical with the previously reported CeTe 3 O 8 phase. Preparative conditions of the various compounds are described and x‐ray diffraction data are reported. The TeO 2 CeO 2 phase diagram was established in the temperature interval from about 650 to 1100°C. Eutectic temperatures are 689°C and 794°C at the TeO 2 and CeO 2 ‐rich sides, respectively.