title: Crystallization kinetics and phase transformation in superionic lithium metaphosphate (Li(2)O-P(2)O(5)) glass system.
abstract: The ionic conductivity of mol% 50Li(2)O-50P(2)O(5) melt quenched glass shows an anomalous increase after its glass transition temperature (T(g)) around 590 K. On further increasing the temperature gradually, the conductivity decreases owing to the devitrification of Li(2)O-P(2)O(5) glass. The evolution of devitrified crystallites was evidenced by XRD patterns. To understand the devitrification process, isothermal and non-isothermal DSC studies have been carried out on mol% 50Li(2)O-50P(2)O(5) glass. T(g) as well as T(c) values are found to increase monotonically with increasing heating rates. Variation of T(g) as a function of heating rates has been investigated to evaluate the lower limiting temperature of T(g) and the activation energy for structural relaxation. Results of the DSC studies indicate (i) single-stage bulk crystallization of the glass, with DSC traces exhibiting a single [Formula: see text] transition, (ii) an order parameter (Avrami constant) of 2.8 ± 0.1, suggesting internal (bulk) crystallization of the glass, (iii) an activation energy for crystallization equal to 121.7 kJ mol(-1) and (iv) the activation energy for structural relaxation, E(g), to be 558.8 kJ mol(-1). The crystallization mechanism is closely associated with the JMA model and the experimental dataset have been fitted to a non-isothermal Avrami expression and the obtained parameters confirm the experimental results.
authors.affiliation: Solid State Ionics Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Benson K
authors.initials: BK
authors.lastname: Money
authors.forename: K
authors.initials: K
authors.lastname: Hariharan