Quantitative calculation of barium vacancy formation mechanism effects on the room-temperature resistance and PTCR effect in donor-doped BaTiO3 ceramics
A modified barium vacancy formation mechanism in donor-doped barium titanate (BaTiO3) ceramics is proposed. Assuming a uniform distribution of barium vacancies at sintering temperature and only oxygen partial pressure and sintering temperature related concentration of unionized barium vacancies, the electrical characteristics have been calculated by solving a differential equation about electron level. The room-temperature resistivity and positive temperature coefficient of resistivity (PTCR) behaviors of donor-doped BaTiO3 semiconducting ceramics have been quantitatively computed. The results pointed out that the room-temperature resistivity changes as a U-type curve with an increase of donor concentration. Moreover, the PTCR effect of BaTiO3 semiconductive ceramics was calculated quantitatively under different conditions. Theoretical and experimental results for BaTiO3 semiconductive ceramics are compared and discussed.