Influence of sintering temperature on structure, physical, and optical properties of wollastonite based glass-ceramic derived from waste eggshells and waste soda-lime-silica glasses

Calcium oxide from discarded eggshells and waste soda-lime-silica were utilized in this study to make wollastonite (CaSiO3) based glass-ceramics. The calcium oxide and silica were made using the melt-quenching process and sintered for 2 hours at 700 to 1000?C. The XRD data verified that the wollastonite crystalline peak appeared at high sintering temperatures, with crystalline phase values of 39.74%, 47.37%, and 48.91% as the sintering temperature increased at 800-1000?C, respectively. Additionally, crystalline size and phase have no obvious change at 800-1000?C, where the intensity has increased by the sintering temperature. The FTIR spectra revealed the wollastonite phase vibration at the wavelength of 501 cm-1, 650cm-1, 715cm-1, 808cm-1, 931cm-1, 2129 cm-1. Additionally, the FTIR spectral confirm the Si-O-Ca vibration band at the wavelength of 650 cm-1. For the optical sample, the value of indirect allowed transition with n=2 is the ideal value of the optical band gap based on a band gap rise from 3.89 to 4.23 eV with increasing sintering temperature. The value n=2 which is the indirect allowed transition is the optimal value of the optical band gap based on the value increase from 3.89-4.23 eV as the temperature increase. The synthesis approach introduced the low-cost method, recycle approach, simple and yet uses cheap starting materials for fabrication of wollastonite glass-ceramics product.