Grain size and Fe2+ concentration‐dependent magnetic, dielectric, and magnetodielectric properties of Y3Fe5O12 ceramics

Y3Fe5O12 ceramics are prepared by the solid state reaction method. Grain size and Fe2+ concentration-dependent magnetic, dielectric, and magnetodielectric properties are investigated systematically. It is found that grain size and Fe2+ concentration increase with increasing sintering temperature, which thus results in increased saturation magnetization while decreased coercive field and remanent magnetization. Three sets of dielectric relaxation are observed in temperature range from 10 to 500 K, which are considered to be originated from quantum tunneling effect of electrons, electron hopping between Fe2+ and Fe3+, and the migration of oxygen vacancies, respectively. Cole-Cole fitting results of relaxation II indicate that a correlation exists among the hopping electrons, and the correlation is strengthened as Fe2+ concentration increases, which in turn results in easier hopping process and decreased activation energy. More interesting, YIG ceramics sintered at 1350 degrees C show both considerable magnetic and dielectric properties at room temperature, opening a new window for the application of YIG as a possible multi-susceptibile single-phase material. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim