Pressure-induced transformations in crystalline and vitreous PbGeO3

Structural transitions in crystalline and vitreous PbGeO3 were studied at pressures up to 20 GPa. Crystalline PbGeO3 was observed to undergo a pressure-induced amorphization between 12-18 GPa. Vitreous PbGeO3 was found to exhibit an amorphous-to-amorphous transition in a similar pressure range. The structural and thermal properties of the pressure-cycled PbGeO3 materials were further studied with high-energy x-ray diffraction and differential scanning calorimetry. The properties were then compared to those of thermally quenched glass and ball-milled PbGeO3 samples. The structure of pressure-amorphized PbGeO3 was found to closely resemble that of ball-milled PbGeO3. However, the thermal properties probed by differential scanning calorimetry exhibited significant differences to those of thermally quenched PbGeO3 glass.