Crystallization Kinetics of the LiBO₂–Nb₂O₅ Glass Using Differential Thermal Analysis

Abstract

The crystallization kinetics in the glass system (100−x)LiBO2−xNb2O5 (5≤x≤20, in molar ratio) prepared via the conventional metal‐plate quenching technique have been studied by isothermal and non‐isothermal methods using differential thermal analyses. X‐ray powder diffraction studies carried out on heat‐treated (500°C) glasses reveal the evolution of lithium niobate crystalline phase along with a minor phase of LiBO2. The exponent n in the Jhonson–Mehl–Avrami (JMA) equation applied to the isothermal process is 2.62, which is in excellent agreement with that obtained under the non‐isothermal process (2.67). The activation energies for crystal growth obtained from JMA equation under isothermal condition, modified Ozawa and Kissinger equations under non‐isothermal conditions, are 293, 311, and 306 kJ/mol, respectively.

Crystallization Kinetics of Amorphous Materials

“…15). In crystallization kinetic studies, as-cast (non-nucleated) and pre-nucleated samples can be used to recognize the effect of increasing and constant number of nuclei on the crystallization mechanism, respectively Prasad & Varma, 2005). For the as-cast (non-nucleated) samples, when the nucleation takes place during thermal analysis, the number of nuclei of the as-cast sample is proportional to the heating rate.…”

“…In the isothermal method, kinetic parameters of amorphous materials crystallization are obtained by monitoring the shift in the crystallization peak as a function of time (Prasad & Varma, 2005). Crystallization peak temperatures, T p and crystallized volume fractions, x, are determined from the thermal analysis curves with respect to time in isothermal method.…”

“…13. Computation of the volume fraction crystallized, x, in isothermal method (Prasad & Varma, 2005) Isothermal investigation of crystallization in amorphous materials can be described by the Johnson-Mehl-Avrami equation as given in Equation 55 (Araújo & Idalgo, 2009;Avrami, 1939Avrami, , 1940Prasad & Varma, 2005).…”

“…In this chapter, crystallization kinetics of amorphous materials was investigated by explaining the crystallization mechanism and the crystallization activation energy in terms of isothermal and nonisothermal methods with different approaches. Different thermal analysis techniques used in crystallization kinetic studies were presented and a correlation between kinetic and structural investigations was made to determine the crystallization mechanism (Araújo & Idalgo, 2009;Malek, 2000;Prasad & Varma, 2005).…”

“…On the other hand, in the nonisothermal method, the sample is heated at a fixed rate and then the change in enthalpy is recorded as a function of temperature. Thermal analysis techniques such as differential thermal analysis (DTA) and differential scanning calorimetry (DSC) are quite popular for kinetic analysis of crystallization processes in amorphous solids (Araújo & Idalgo, 2009;Malek, 2000;Prasad & Varma, 2005).…”