Grain size and Fe~(2+) concentration-dependent magnetic, dielectric, and magnetodielectric properties of Y_3Fe_5O_(12) ceramics

摘要

Y_3Fe_5O_(12) ceramics are prepared by the solid state reaction method. Grain size and Fe~(2+) concentration-dependent magnetic, dielectric, and magnetodielectric properties are investigated systematically. It is found that grain size and Fe~(2+) 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 Fe~(2+) and Fe~(3+), 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 Fe~(2+) concentration increases, which in turn results in easier hopping process and decreased activation energy. More interesting, YIG ceramics sintered at 1350℃ 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.