Thermal analysis and crystallization of the glasses inside the BaO-SrO-TiO2-NaPO3 system

The xBa(0.5)Sr(0.5)TiO(3)-(1 - x)NaPO3 (x = 0-0.20 mol%) glasses were prepared by the conventional melt-quenching method. The amorphous state of the samples was verified by X-ray diffraction. The density, molar volume, glass transition temperature (T (g)), micro-hardness and the crystallization temperature (T (c)) are determined for each glass. It is found that they depend strongly on the chemical composition of the glasses. The results of the micro-hardness show an increase in the H (v) parameter with the Ba0.5Sr0.5TiO3 content. The crystallization of glasses is made by submitting samples to heat treatments, and the crystallized phases are identified by XRD. The kinetic of the crystallization is carried out by thermal analysis using DSC technique. The mechanism of crystallization is proposed according to the determined activation energy (E (a)) and the Avrami parameter (n). The structural approach of the glasses was realized out by IR spectroscopy. This technique has highlighted the co-existence of different phosphate and titanium structural units in the glassy-matrix.