Kauzmann temperature and the glass transition

Kauzmann temperature was investigated on the As2Se3 and As2S3 bulk glasses. Novel StepScan DSC technique was used to separate processes during the glass transition on both reversible and irreversible parts. This method is necessary to obtain correct information especially when undercooled melt undergo glass transition and the exothermic change is masked by the increase of total heat flow. It was found that Kauzmann temperature of As2Se3 bulk glass coincides with the low temperature onset in the glass transition range. Kauzmann temperature of As2S3 was found markedly bellow the glass transformation range. From that follows that the glass transition of As2Se3 can be considered as thermodynamic one, contrary to the glass transition of As2S3. From this point of view As2Se3 is an ideal glass contrary to As2S3 glass that preserves to a certain extent the undercooled melt nature.