Investigations of Ti-substituted CuFeO2 ceramics on the structure, defects, the local electron density and magnetic properties

Abstract CuFe 1- x Ti x O 2 (0 ≤ x ≤ 0.08) ceramics are synthesized by solid state reaction method to investigate the effect of Ti substitution on the microstructure, vacancy-type defects, the local electron density, and magnetic properties. The XRD and Raman spectra results show that all experimental samples possess the characteristic peak of CuFeO 2 ceramics. SEM observations indicate that Ti substitution has obvious influence on the morphologies of experimental ceramics, and the microvoids increases significantly with increasing Ti content. Positron annihilation lifetime and Doppler broadening spectra results indicate that the vacancy concentration increases rapidly and then reaches a higher platform (> 35%) as x > 0.01, and Ti substitution does not change the defects species in CuFe 1- x Ti x O 2 ceramics. The electron density decreases with increasing x and then reaches a low plateau (≈ 5.7) at x = 0.08. The χ - T curves reveal that the T N1 is independent of Ti content, while, the T N2 decreases with increasing x at x = 0.00-0.02 and even disappears in the magnetization curves as x > 0.02. The M-H curves indicate that the coexistence of weak ferromagnetism and antiferromagnetism for all the samples could be found. The possible reasons for the above observations are discussed in detail.