Topotactic reduction and reoxidation of hexagonal RCu0.5Ti0.5O3 (R = Y, Eu-Lu) Phases

Hexagonal AMO2 and AMO3 phases have the same basic structure, and intermediate compositions for this structure have been prepared by topotactic oxidation of AMO2 phases such as RCuO2, where R is a trivalent rare earth cation. We now find that such intermediate phases can also be prepared by topotactic reduction of hexagonal RCu0.5Ti0.5O3 (R = Y, Tb-Lu) phases. Our TGA and magnetic susceptibility studies indicate a formula of RCu0.5Ti0.5O2.78 for these reduced phases. Topotactic reoxidation occurs on heating these phases to 400 °C in air.