Crystallization and Conduction Mechanisms on Amorphous PbTiO3

Glass system ofxPbTiO3–(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 thex=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 ofx=80,x=70, 1st crystallization ofx=50, and 2nd crystallization ofx=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 ofx=70, the PbTiO3crystalline did not form a tetragonal phase right after crystallization temperature but a cubic phase. By further annealing the PbTiO3crystalline 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.