Silver - Cerium - Selenium

Peter Rogl

Introduction

[65Lor], [68Jul] and [73Jul] agreed on the existence of a ternary selenide which had the Th₃P₄-type of structure (cI28) and a small region of homogeneity deriving from the binary compound Ce₂Se₃ by a substitutional mode, according to the crystal chemical formula: Ce_5+xAg_1-3x⃞_2xSe₈, 1/3 > x > 0.24 (Table 1). Samples were prepared by heating compacted powder mixtures of Ag₂Se and Ce₂Se₃ in sealed silica capsules at temperatures above 1000°C [68Jul]. A different method starting from oxalates, involving calcination at 900°C, and reaction under H₂Se at 1200°C in graphite crucibles is described by [65Lor...