Crystallization and Conduction Mechanisms on Amorphous PbTiO₃

Glass system of xPbTiO₃–(100-x)B₂O₃ (x = 50, 70, 80) was produced by twin-roller quenching method. Glass transition temperatures were 541.3°C, 440.0°C, and 467.8°C for the x =80, 70, and 50, respectively with heating rate of 10°C/min. Crystallization temperatures(activation energies) were 517.5°C (4.10 eV), 526.5°C (3.72 eV), 547.2°C (3.79 eV), and 557.5°C (3.97 eV), for the samples of x=80, x=70, 1st crystallization of x=50, and 2nd crystallization of x=50, respectively. It was revealed that this sample crystallized two-dimensionally analyzed by modified Ozawa method. From the X-ray diffraction experiments of heat-treated samples of x=70, the PbTiO₃ crystalline did not form a tetragonal phase right after crystallization temperature but a cubic phase. By further annealing the PbTiO₃ crystalline became a tetragonal ferroelectrics. From the temperature- and frequency-dependence of dielectric constants, it was revealed that two conduction mechanisms are responsible for the dielectric response, and the transition frequency was thermally activated. The activation energies above and below the crystallization temperature are 1.1 and 0.7 eV, respectively.