Sintering Temperature Effect on Structural and Optical Properties of Heat Treated Coconut Husk Ash Derived SiO₂ Mixed...

In this work, waste coconut husk ash was used to prepare a ZnO-SiO₂ composite. Solid-state technique was used to fabricate the composite due to its producibility, simple procedure as well as lower production cost. At high sintering temperatures ranging from 600 °C to 1000 °C, the X-ray diffraction (XRD) peaks of the Zn₂SiO₄ showed high intensity, which indicated high crystallinity. Furthermore, the formation of broad bands of ZnO₄, Si-O-Si, and SiO₄ were detected by Fourier transform infrared (FTIR) spectroscopy and the bands became narrower with the increment of sintering temperature. Besides, the morphological image from field emission scanning electron microscopy (FESEM) showed the formation of densely packed grains and smooth surface composite with the increase of sintering temperature. Upon obtaining the absorbance spectrum from Ultraviolet-Visible (UV-Vis) spectroscopy, the optical band gap was calculated to be 4.05 eV at 1000 °C. The correlation between the structural and optical properties of ZnO-SiO₂ composite was discussed in detail.