Electrical properties of air-fired Nb-doped SrTiO3 with excess titania

Abstract

Abstract Electrical properties of Nb-doped SrTiO3 ceramics sintered above and below the liquid phase formation temperature in air were examined. High apparent dielectric constants were obtained when the donor level was ≥0.8 at%. The high dielectric constants and relatively high loss tangent, along with the I-V characteristics and color of the samples, implied conductive grains and weakly insulative grain boundaries. A weak dielectric relaxation was observed at the low radio frequencies (10-105 Hz) in the temperature region -50[ddot] -125[ddot]C. The ionic polarization model proposed by Skanavi was applicable to the dielectric relaxation, which supports strontium vacancy compensation for Nb donors.