High Oxygen Pressures and the Stabilization of Unusual Oxidation States of Transition Metals: Application to Iridium Oxides

Abstract

High oxygen pressures have been developed in different media: gas (500 MPa), in liquid phase using oxidizing solutions (500 MPa) and in the solid phase through the "in situ" thermal decomposition of KClO₃. The main objective of the development of high oxygen pressures was the stabilization of the highest oxidation states of transition elements. For the same Mⁿ⁺ cation, the increase of the n value induces a decrease of the M-O distance. Such a variation being larger than the compression effect on oxides, the stabilization of the highest oxidation states of transition metals appears a fruitful route for investigating the correlations between the covalency of the chemical M-O bonds and the resulting physico-chemical properties of the corresponding oxides.