Characterization of oxygen vacancy defects in Ba1-xCaxTiO3 insulating ceramics using electron paramagnetic resonance technique

The electron paramagnetic resonance (EPR) technique was employed to detect oxygen vacancy defects in the tetragonal Ba1-xCaxTiO3 (x = 0.03) ceramics (BCa3T) prepared via the mixed oxide route at 1300-1500 degrees C. In the rhombohedral phase below -100 degrees C, an EPR signal at g = 1.955 appeared in the insulating BCa3T with an electrical resistivity of 10(8)Omega cm and was assigned to ionized oxygen vacancy defects. BCa3T prepared at 1300 degrees C showed a temperature-stable X6S dielectric specification (epsilon' = 1750). Three types of vacancy defect, namely, Ba, Ti, and O vacances, could coexist in BCa3T owing to the partial Ti-site occupation by Ca2+. (C) 2016 The Japan Society of Applied Physics