Stabilization of unusual oxidation states under high oxygen pressures: A challenge for the solid state chemist

Abstract

Due to the increase of the covalency of chemical bond versus the oxidation state and the correlations with physical properties, the stabilization of the highest oxidation states of transition elements is a challenge for a better knowledge of materials. The development of high oxygen pressures has lead to the stabilization of new oxidation states in oxide-lattice (Fe(IV), Fe(V), Co(ZIZ), Co(ZV), Ni(IIZ), Cu(III)…).

Due to the strong strength of the Cu(IZI)-0 bond when the d⁸ low-spin state is observed, we have prepared Au(III) oxides with a layered structure: Ln₂ Li_0.50 Au_0.50 (Ln = rare-earth elements). A comparison between Cu(III) and Au(III) oxides is developped.