Influence of Zn2+ doping on the microstructure and magnetic properties of CuFeO2

The mineral delafossite CuFeO₂ exhibits triangular spin frustration with strong magnetoelectric coupling and unique magnetic properties. In this work, the crystal structure, microstructure, oxidation states, and magnetic properties of synthetic CuFe_1-xZn_xO₂ samples have been systematically studied with a view to understanding the effect of small amounts of the diamagnetic Zn²⁺ ion on the magnetoelectric properties of CuFeO₂. Samples were confirmed by XRD as having a single-phase delafossite structure, although the introduction of Zn²⁺ resulted in distortion of the crystal lattice. Addition of Zn²⁺ also increased the particle size and the number of pores, but did not change the oxidation states of either the Cu or Fe. Magnetic susceptibility measurements show that Zn²⁺ disrupted the antiferromagnetic structure of the samples, and resulted in generation of significant ferromagnetism. Overall, the magnetic properties of CuFeO₂ are closely related to ionic substitution, lattice distortion and microscopic defects.