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Isothermal DTA study on crystallization of mica composition-based glass

1997; Elsevier BV; Volume: 215; Issue: 2-3 Linguagem: Inglês

10.1016/s0022-3093(97)00084-7

1873-4812

Kangguo Cheng, Julin Wan, Qiang Cai,

Phase-change materials and chalcogenides

Isothermal differential thermal analysis (DTA) was used to study the crystallization of a glass with a composition close to that of mica (NaMg3AlSi3O10F2), with TiO2 added as a nucleating agent. Two distinct crystallization exotherms in DTA were attributed to the formation of MgTi2O5 followed by NaMg3AlSi3O10F2. By using the Johnson-Mehl-Avrami equation, the activation energy for precipitation of each crystalline phase was evaluated and the crystallization mechanism was analyzed. Results indicate that NaMg3AlSi3O10F2 growth is a two-dimensional process, controlled by the crystal-glass interface reaction. The average value of activation energy is 256 ± 11 kJ/mol and 275 ± 7 kJ/mol corresponding to MgTi2O5 and mica, respectively.