Crystallization kinetics of new Ge20Se60Sb20−xAgx (0 ≤ x ≤ 20 at. %) glasses

The crystallization kinetics of the newly Ge20Se60Sb20−xAgx (0 ≤ x ≤ 20 at %) chalcogenide glasses was characterized by DSC under non-isothermal conditions. Two well-defined crystallization exotherms were exhibited in the DSC traces for all Ag-containing glasses corresponding to the multiple-stage crystallization mode. The kinetic exponents n and m, that determine the crystallization reaction mechanism in the glasses, were obtained using the experimental values of the crystallized volume fraction, χ. The initial crystallization stage is governed by bulk nucleation with one-dimensional growth. For the second exotherm the crystallization mechanism transforms from two-dimensional growth for x = 0 into one-dimensional growth for x = 20 at %. The activation energies for the glass transition, the first and second crystallization stages have been obtained. It was found that the crystallization products are the ternary phase Ag8GeSe6 for the first crystallization exotherm and the phases GeSe2 and Sb2Se3 for the second crystallization exotherm.