Effect of complex defects on the origin of giant dielectric properties of Mg2+−doped BiFeO3 ceramics prepared by a precipitation method

Abstract

Nanocrystalline powders of BiFe1-xMgxO3 (x = 0, 0.05, and 0.10) were prepared via a co−precipitation method. This produced a dense ceramic microstructure when sintering the compacted nanocrystalline powders at 800 °C for 3 h. A main phase of BiFeO3 with a small number of impurity phases was confirmed to exist in the sintered ceramics. High ε′ values of 103-105 in the temperature range of 200–473 K were obtained. Dielectric relaxation behavior was studied over a wide temperature range. The low− and high−temperature dielectric relaxations originated from electron hopping between Fe2+↔Fe3+ and the interfacial polarization associated with the long−range motion of free charge carriers, respectively. To describe the dielectric properties of the Mg2+−doped BiFeO3 ceramics, theoretical calculations were performed to investigate the most preferable formation of complex defects. It was found that the dopant concentration had an effect on the defect shapes and dielectric properties.