New Insights of the Solid State Transformations in the Ag-Se-Ge System : a Mechanical Spectroscopy Study

Abstract
a study of degrees of freedom exhibited by partially crystallised material of the system Ag-Se-Ge is reported. Mechanical spectroscopy reveals 3 processes in the temperature range 250K to 330K. Two processes at 298K and 315K are assigned to solid state transformations in Ag₈GeSe₆ crystallites. A broad relaxation process exhibiting a high activation energy is connected to cooperative events assumed to occur in the glassy matrix. The two first processes also manifest in DSC experiments. The high temperature one is definitively attributed to allotropic transformation of Ag₈GeSe₆ crystalline phase. The low temperature one is reported for the first time in this paper and is attributed to the transformation of a crystalline metastable phase induced by constraints imposed by the surronding glassy matrix.