Effect of oxygen partial pressure during sintering on electric properties of BiFeO3-based piezoelectric ceramics

The effects of oxygen partial pressure (pO(2)) during sintering and post-annealing treatment on the microstructure and electrical properties of Mn-added 0.3BaTiO(3)-0.1Bi(Mg1/2Ti1/2)O-3-0.6BiFeO(3) ceramics were investigated. The ceramics sintered at pO(2) of 0.1-1 atm showed pinched polarization-electric field (P-E) loops, while the ceramics sintered in nitrogen gas could not be measured due to dielectric breakdown. By annealed at 800 degrees C for 5 h and cooled slowly, the ceramics showed increased remanent polarizations although their P-E loops were still pinched. When the as-sintered ceramics were annealed at 800 degrees C for 5 h and then quenched into water, well-developed ferroelectric hysteresis loops were observed. These results were discussed with grain size and defect dipoles consisted of oxygen vacancies and bismuth vacancies or iron ions with a different valence. (C) 2019 The Ceramic Society of Japan. All rights reserved.