ABSTRACT
The chemistry of thallium oxides, especially of thallium(III), has become important in the wake of the discovery of superconductivity in thallium cuprates. A knowledge of thallium oxide chemistry is therefore essential for proper appreciation of the chemistry of superconducting thallium cuprates. The foregoing brief survey of thallium oxides shows that unusual electronic properties result whenever there is a possibility of mixed valency for thallium. Another factor that contributes to the interesting electrical properties of thallium oxides is the proximity of Tl states to the 0 states and the possibility of modulating the latter in the presence of electropositive countercations. These aspects of thallium oxide chemistry are of special relevance to the chemistry of the superconducting thallium cuprates.
