An elucidating study on physical and structural properties of 45S5 glass at different sintering temperatures

• Decomposition of oxide materials in 45S5 glass generated non-linked porosity.
• Sintering of 45S5 glass at 800 °C suggested the transformation into crystalline phases.
• Increase of sintering temperatures increased size of air trap in glass.

This paper presents a study of physical and structural properties of 45S5 bioactive glass (BG) at different sintering temperatures. The 45S5 BG, one of the most important formulations, was composed of 45% SiO2, 24.5% Na2CO3, 24.5% CaCO3 and 6% P2O5. The aim of this research was to gain a better understanding on the effect of heat treatment towards phase transformation of the 45S5 BG. Each composition of the 45S5 BG was sintered at three different temperatures, which were 800 °C, 1000 °C and 1200 °C. The formation of crystallization or phase changes before and after the heat treatment was being identified using X-ray diffraction analysis. Bonding of the BG before and after sintering was being investigated using Fourier transform infrared spectroscopy while morphology of the 45S5 BG was determined by field emission scanning electron microscopy (FESEM). The X-ray pattern indicated the presence of silicate and phosphate in the glass system. Amorphous glassy phases with sodium calcium silicate (Na2Ca3Si6O16) and sodium calcium phosphate (NaCaPO4) were observed in the sintered glass. A decrement in density was due to formation of additional porosity which occurred due to decomposition of oxide materials in the glass. This was confirmed by FESEM results, which proved an increase in the porosity at high temperature.