Non-isothermal crystallization of lithium germanophosphate glass studied by different kinetic methods

Crystallization kinetics of 22.5Li2O•10Al2O3•30GeO2•37.5P2O5 (mol%) glass was studied under non-isothermal condition using the differential thermal analysis (DTA). The study was performed by using the first crystallization peak temperature (Tp1) which belongs to the precipitation of LiGe2(PO4)3 phase in the glass. The activation energy of glass crystallization (Ea) was determined using different isokinetic methods. The dependence of Ea on the degree of glass-crystal transformation (α) was studied using model-free isoconversional linear integral KAS (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa) methods. It was shown that the Ea varies with α and hence with temperature and consequently the glass/crystal transformation can be described as a complex process involving different mechanisms of nucleation and growth. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 34001 and Grant no. 172004]