Thermokinetic behaviour of Ag-doped (GeS2)50(Sb2S3)50 glasses

Abstract The effect of Ag-doping on the thermokinetic behavior (cold crystallization and structural relaxation kinetics, glass-forming ability) of the Ag y [(GeS 2 ) 50 (Sb 2 S 3 ) 50 ] (100 − y) glasses was studied by using differential scanning calorimetry, Raman spectroscopy and X-ray analysis – compositions up to y = 25 were included in the study. Structural relaxation kinetics was found to be only very weakly influenced by the Ag-doping; the following Tool-Narayanaswamy-Moynihan parameters were determined (within a 10% variation) for the majority of the glasses: activation energy 400 kJ mol − 1 , non-linearity parameter 0.72, non-exponentiality parameter 0.85. On the other hand, the glass transition temperature decreased significantly with increasing Ag content – the effect can be explained by dilution of the original glassy matrix. Combination of these findings with the corresponding Raman spectra has shown that it is the Ge-S structural units that carry the main portion of the relaxation motions. Regarding the crystallization behavior, the Ag-doping led to decreased glass-forming ability and increased tendency of the glasses towards crystallization. The Ag-rich compositions exhibited during heating well-developed crystallization peaks driven by the autocatalytic Sestak-Berggren kinetics. The X-ray analysis has shown that in case of the Ag-rich compositions Sb and argyrodite crystallites tend to form during the melt-quench.