Comparative study of thermal stability and crystallization kinetics of 70B 2O 3–30Bi 2O 3 and 70B 2O 3–30PbO glasses

Abstract

Glasses with compositions 70B 2O 3–30Bi 2O 3 and 70B 2O 3–30PbO have been prepared and studied by differential thermal analysis (DTA). The crystallization kinetics of the glasses were investigated under non-isothermal conditions. From the dependence of glass-transition temperature ( T g ) on heating rate, the activation energy for the glass transition was derived. Similarly the activation energy of the crystallization process was determined. Thermal stability of these glasses were achieved in terms of the characteristic temperatures, such as glass-transition temperature, T g , onset temperature of crystallization, T in , temperature corresponding to the maximum crystallization rate, T p , beside the kinetic parameters, K( T g ) and K( T p ). The results revealed that 70B 2O 3–30PbO is more stable than 70B 2O 3–30Bi 2O 3. The crystallization mechanism is characterized for both 70B 2O 3–30Bi 2O 3 and 70B 2O 3–30PbO glasses (kinetic exponent n=2.06 for 70B 2O 3–30Bi 2O 3, and n=3.03 for 70B 2O 3–30PbO). The phases at which the glass crystallizes after the thermal process were identified by X-ray diffraction.