Size dependence of magnetic and dielectric properties in YCr0.5Fe0.5O3 ceramics

Abstract

The YCr0.5Fe0.5O3 ceramics with different sintering temperatures (TS) have been synthesized by a sol-gel method, and the structural, magnetic and dielectric properties are studied. With the decrease of TS, continuous decrease of grain size is evidenced via the micromorphology analysis. Due to the competition between the single ion magnetic anisotropy and the antisymmetric Dzyaloshinsky-Moriya interaction, the total magnetization becomes zero at the compensation temperature (TComp) in the presence of a lower magnetic field, and the TComp exhibits size dependent behavior. With the decrease of grain size, the TComp becomes lower due to the increase of uncompensated spins. Meanwhile, the TComp is adjustable by the magnetic field, and a larger external field drives the TComp to lower temperature. After cooling the samples in magnetic field, the magnetic anisotropy is established, which results in a positive exchange bias (EB) effect below the TComp. The decrease of TS would increase the ferromagnetic component, which leads to the decrease of EB field (HEB). The dielectric measurements suggest that the samples of TS = 900 and 800 °C possess large permittivity accompanied with dielectric relaxation near room temperature, and the dielectric relaxation which arises from the single-ionized oxygen vacancies moves to higher temperature with the decrease of TS.