Pavla Pustková

Kinetic phenomena in non-crystalline materials studied by thermal analysis

The structural relaxation and viscosity behavior of Ge38S62 glass has been studied by thermomechanical analysis. The relaxation response to any thermal history is well described by the Tool-Naraynaswamy-Moynihan model. The apparent activation energy of structural relaxation is very close to the activation energy of viscous flow (Eη=478±12 kJ mol-1). However, the activation energy of crystal growth obtained by optical microscopy is about one half of this value. Similar result has been obtained from isothermal DSC measurement (Ea=220±20 kJ mol-1). The kinetic analysis of these data reveals interface controlled crystal growth with zero nucleation rate.

Structural relaxation of amorphous Ge38S62 studied by length dilatometry and calorimetry

The structural relaxation of Ge38S62 glass has been studied by length dilatometry and calorimetry. The Tool-Narayanaswamy-Moynihan model was applied on obtained data of structural relaxation and parameters of this model were determined: Δh*= 483±2 kJ mol-1, ln(A/s)= -81±1, β= 0.7±0.1 and x=0.6±0.1. Both dilatometric and calorimetric relaxation data were compared on the basis of the fictive relaxation rate. It was found that the relaxation rates are very similar and well correspond to the prediction of phenomenological model.