Giant permittivity and low dielectric loss of SrTiO3 ceramics sintered in nitrogen atmosphere

The dielectric properties of SrTiO3 ceramics sintered in nitrogen (N-2) exhibit a weak temperature- and frequency-dependent giant permittivity (>10(4)) as well as a very low dielectric loss (mostly < 0.02) over a broad temperature range from -100 to 200 degrees C. Based on the results of ac conductivity and structural analysis, the giant permittivity and low dielectric loss were due to the fully ionized oxygen vacancies and giant defect-dipoles. When further sintering these ceramics in air, the materials exhibit a large temperature- and frequency-dependent high dielectric loss, which were due to the ionization and motion of oxygen vacancies. (C) 2014 Elsevier Ltd. All rights reserved.