Hydrothermal synthesis of Cd₃TeO₆ oxide powders

Abstract

Hydrothermal preparation of a transparent wide-gap conductor Cd₃TeO₆ from CdO, TeO₂, H₂O₂, and alkali hydroxide was explored. The reaction without alkali hydroxide yielded only a small amount of Cd₃TeO₆, and NaOH gave a better yield than LiOH and KOH. The reactions without H₂O₂ did not form Cd₃TeO₆ at all. This observation indicated that H₂O₂ oxidized tellurium (IV) to the oxidation state VI in this system. The reactions at 240°C, the highest temperature available in this study, gave a better yield of Cd₃TeO₆ than the reactions at lower temperatures. After these optimizations, Cd₃TeO₆ was obtained as the dominant product.