Relaxation behavior and electrical inhomogeneity in 0.9BaTiO₃-0.1Bi(Mg_1/2Ti_1/2)O₃ ceramic

In this paper, the relaxation behavior and electrical inhomogeneity of the 0.9BaTiO₃- 0.1Bi(Mg_1/2Ti_1/2)O₃ ceramic which exhibits outstanding temperature stable dielectric and energy storage properties are investigated. The relaxation process is well described by the empirical Vogel-Fulcher law, also indicating a freezing process in the system simultaneously. Such a freezing process is also observed in the “Vogel-Fulcher” shaped temperature dependence of the universal relaxation exponent n. Furthermore, the electrical inhomogeneity, showing up as two dielectric anomalies in the temperature dependence of the dielectric constant, is ascribed to the compositional inhomogeneity between grains and grain boundaries. The grain and grain boundary contributions to the total polarization are separated by analyzing the complex impedance spectroscopy with equivalent circuit model. Finally, the compositional inhomogeneity is manifested by the confocal Raman microscopy, indicating that the grain is rich in BaTiO₃, whereas the grain boundary has Bi(Mg_1/2Ti_1/2)O₃ concentrations.