A novel method to study crystallization of glasses

A novel method to study crystallization behavior in non-crystalline materials has been developed. The method is based on slowing down of sample deformation by viscous flow above the glass transition due to macroscopic crystal growth. This process might be detected by thermomechanical analysis (TMA). The influences of sample length, applied force and heating rate have been examined. Newly developed method has been used to study crystallization in (GeS2)0.3(Sb2S3)0.7 glass. It was found that a typical TMA measurement reasonably well corresponds to previously reported crystal growth kinetics by means of optical microscopy. The activation energy obtained from the shift of extrapolated TMA onset temperature with heating rate (E = 286 ± 8 kJ mol−1) is very similar to the activation energy of Sb2S3 crystal growth in (GeS2)0.3(Sb2S3)0.7 glass (EG = 288 ± 7 kJ mol−1) from optical microscopy measurements. The TMA curve does not match with non-isothermal DSC curve taken at comparable experimental conditions. It seems that TMA measurement reflects early stages of crystal growth that are not associated with thermal effects measured by DSC.