Crystallization and sintering of glasses formulated from different theoretical contents of leucite (L) and bioglass 45S5 (Bg) (LxBg(100-x) x:25, 30, 40, 50): A comparative study on raw materials influence

Abstract

Glasses were synthesized with different theoretical contents of leucite and Bioglass 45S5 using different raw materials for the contributions of Al2O3 and K2O in order to study crystallization and sintering, and to study raw materials and composition influence on those processes. Each proposed composition was produced by duplicate, using different raw materials for the addition of K2O, Al2O3 and SiO2; on the one hand using analytical grade reagents and on the other natural minerals (quartz (SiO2) and feldspar (KAlSi3O8)). Glasses were characterized by differential thermal analysis (DTA) and hot stage microscopy (HSM), and thermally treated glasses were studied by X-ray diffraction (XRD). It could be clarified that the sintering occurred prior to the onset of crystallization and the crystalline phases developed in all the samples studied were sodium calcium silicate (Na2CaSi2O6) and tetragonal leucite (KAlSi2O6), which crystallized in this order. Glasses made from analytical grade raw materials showed a slight difference regarding phase crystallization temperature, which occurred at a lower temperature than those produced from natural minerals. Sodium calcium silicate showed a dependence of retained phosphorous in solid solution as a function of glasses compositions, taking as a base other works where the variations of the cell parameters of this phase with temperature were studied.