Improving the magnetic and dielectric properties of Cu1−xHoxFeO2 nanoceramics by tuning the vacancy defects and Fe valence state. Issue 10 (15th May 2023) - Dai, Haiyang
Abstract: In this study, Cu1− x Ho x FeO2 nanoceramics were synthesized by sol-gel method to investigate the influence of the vacancy defects and Fe valence state tuning on the magnetic and dielectric properties of Cu1− x Ho x FeO2 nanoceramics. XRD and Raman analysis indicated that Cu1− x Ho x FeO2 nanoceramics with single-phase delafossite structure were synthesized by sol-gel method; Ho 3+ ions had replaced the Cu ions in CuFeO2 and resulted in lattice deformation. XPS analysis indicated that Ho 3+ substitution could tune the Fe valence state, but did not cause significant change in oxygen vacancy concentration. The results of positron annihilation lifetime spectroscopy revealed that cation vacancies concentration in the interface region could be effectively tailored by Ho 3+ substitution. The magnetic measurements indicated that Ho 3+ substitution enhanced the magnetic transition temperatures and magnetization of Cu1− x Ho x FeO2 samples, which could be mainly attributed to the cation vacancies concentration in the interface region and Fe 2+ concentration. Most interestingly, the Cu1− x Ho x FeO2 nanoceramics exhibited giant dielectric characteristic, which was attributed to the charge ordering of Fe 3+ and Fe 2+ .