Synthesis and characterization of CuFeO2+δ delafossite powders

Effects of oxygen off-stoichiometry have been investigated on CuFeO2+δ delafossite-type powders prepared by solid state reaction. Materials annealed at different temperatures under air atmosphere were compared. Thermogravimetric analysis coupled with X-ray structural analysis showed that a powdered CuFeO2 can be oxidized up to CuFeO2+δ with δ = 0.18. Electrical measurements confirm the existence of oxidized CuFeO2+δ phases. Particular attention is paid to the correlation between oxidation process and phase stabilities in the CuFeO2 and copper spinel phase system.