Effect of Zr substitution on the microstructure and magnetic properties of CuFeO₂ ceramics

Abstract

To specify the modulating mechanism of Zr substitution on the microstructure and magnetic properties of the delafossite type oxides CuFe_1−xZr_xO₂ (x = 0–0.10), the multiferroic ceramics are synthesized by the solid-state reaction method. The microstructure and properties of the obtained samples are characterized by X-ray diffraction, scanning electron microscope, Raman spectroscopy, positron annihilation lifetime spectra and physical property measurement system. The XRD results indicate that all samples form delafossite structure, and Zr⁴⁺ substitution induces the shift of the main diffraction peaks. SEM measurements demonstrate that Zr substitution suppresses the grain growth. Raman spectra results show that Zr substitution changes the degree of polarization and intragranular stress for the CuFe_1−xZr_xO₂ samples. Positron annihilation results suggest that vacancy-type defects exist in all samples, and the concentration and size of defects are influenced significantly by Zr substitution. The M–T curves of all samples display two successive magnetic transition temperatures T_N1 and T_N2, and the substitution of Zr for Fe tends to suppress the low ferromagnetic interactions in the magnetic structure. Simultaneously, all samples exhibit macroscopic weak ferromagnetic behavior at low temperature.