Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Cobalt(II) tellurates with the composition CoTeO₄, CoTeO₄.1/2 H₂O and Co₃TeO₆ were prepared. The first two are cubic with octahedral coordination around the cobalt atom and with TeO₆ octahedra joined at the edges. In Co₃TeO₆, which is isostructural with Ni₃TeO₆, the TeO₆ octahedra are isolated. At least one cobalt atom is tetrahedrally coordinated by oxygen atoms. The high values of the temperature independent paramagnetism, 11 m³ kg^-1, and the Weiss constant, Θ = -64 K, indicate marked magnetic exchange interaction. The thermal decomposition of all three tellurates leads to formation of cobalt tellurates and finally to CoO and TeO₂. At laboratory temperature all three substances are paramagnetic with μ_eff values corresponding to divalent cobalt.