Conversion of Agricultural Wastes into Value-Added Silicate-Based Glass Ceramics for Wide Band Gap Application

Abstract

Wheat husk ash (WHA) and sugarcane leaf ash (SCLA) are secondary wastes of agricultural residues. The ashes of these two wastes are heat-treated at 1400 °C for 6 h. These samples are analysed by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible (UV–visible) spectroscopy. Both samples largely contain silicates, along with minor amounts of alkali and alkaline earth oxides. XRD confirmed the presence of cristobalite, tridymite, and quartz along with an amorphous matrix. The amount of quartz is ~ 5% along with amorphous phase in WHA sample. Contrary to this, SCLA precursor sample contained higher content of two different crystalline phases i.e. 57% (cristobalite and tridymite) with 43% amorphous phase. The optical band gaps are 3.88 eV and 3.70 eV for SCLA and WHA-derived samples, respectively. The dielectric constant of SCLA and WHA samples is 4.97 and 4.81, respectively. The present findings demonstrate that the above-mentioned secondary wastes can be directly converted, using solid state reaction technique, into wide band gap, low dielectric constant materials for engineering and medical applications.