As-Se系ガラスの熱処理と結晶化

抄録

Glasses in the system As-Se were heat-treated at temperatures higher than T_g (glass transition temperature) for 20-340 hours in order to study the relation between the crystalline phase formed in a glass and the structure of the glass.
The crystalline phases formed during the thermal treatment were identified by X-ray diffraction technique as hexagonal Se in the case of Se glass and As₂Se₃ in the case of As₂Se₃ and AsSe glasses.
The crystallization of Se glass, which was initiated by homogeneous nucleation, was determined by density change, but heterogeneous crystallization was observed in As₂Se₃ glass and the crystal growth was measured by means of metallurgical microscopy as functions of temperature and time.
The activation energies for nucleation (E_N) and for crystal growth (E_G) calculated from the Arrhenius plots of the induction periods of crystallization and the growth rate G are as follows; E_N=29.4±0.8kcal/mole and E_G=12.6±2.2kcal/mole for Se glass, and E_N=41.2kcal/mole and E_G=26.7kcal/mole for As₂Se₃ glass. They turned out to be much smaller than the activation energy for viscous flow at constant pressure or than the cleavage energy of a single bond such as Se-Se bond (44kcal/mole) or As-Se bond (42kcal/mole.).