Viscosity and crystallization mechanism of cesium loaded iron phosphate glasses

• Melt viscosity of cesium loaded iron phosphate glasses is measured and reported for the first time.
• Viscosity – temperature followed Arrhenius model.
• Activation energy of viscous flow is strongly correlated to glass transition temperature of the glasses.
• Process of crystallization of cesium loaded glass by approximation-free kinetic method to understand the mechanism.
• Cesium loaded IPG and IPG shows bulk crystallization mechanism.

This paper describes the melt viscosity behaviour and the crystallization mechanism of a series of iron phosphate glasses. High temperature viscosity measurements were carried out on pristine iron phosphate glass and a series of cesium loaded iron phosphate glasses in order to understand the effect of addition of Cs2O on viscosity of iron phosphate glasses. Activation energy of viscous flow was estimated from the experimental data by applying Arrhenius model of viscosity–temperature relationship. Activation energy of viscous flow is observed to be strongly correlated to glass transition temperature of these glasses. Fragility of iron phosphate and cesium loaded iron phosphate glass systems were also evaluated in region of high temperature. Crystallization of these glasses was studied using thermal analysis techniques. Temperature integral approximation free method was utilized to evaluate the kinetic parameters such as activation energy of crystallization (Ec) and Avrami exponent (n). The value of Avrami exponent ‘n’ obtained showed that the glasses under present study crystallize via bulk crystallization mechanism, i.e., nucleation and three dimensional growth.