Re-examination of the phase transitions in solid solutions of perovskite-type oxides

Abstract

The successive phase transitions in BaTi_1−xZr _x O₃ and BaTi_1−xSn _x O₃ systems have been re-examined. Ceramic specimens of these solid solutions for various compositions were prepared by ordinary sintering techniques. The temperature dependencies of the complex dielectric constant and pyroelectric currents of these specimens were measured in order to determine the temperatures of the phase transitions. The behavior of the dielectric constants near the lower phase transitions become smeared with increasing Zr or Sn concentration, however, the imaginary part of the dielectric constant and the pyroelecric currents show clear anomalies. The phase diagrams for these systems, deduced from these measurements, have been analyzed by means of Matsubara-Yoshimitsu theory. The agreements between the experimental facts and theoretical predictions are quite satisfactory.