Ceramics-Silikáty 66, (1) 95 - 103 (2022)

This study aimed to explore the effect of thermal treatments on the phase composition and electrical properties of an Na₂FeSiO₄ precursor. Samples were prepared from NaOH, Fe(NO₃)₃.9H₂O, rice husk silica, and C₆H₈O₇.H₂O using the sol-gel method. The samples were thermally treated at a temperature range of 350 - 475 °C with a holding time of 10 hours. The functional groups of each sample were identified using Fourier transform infrared (FTIR) spectroscopy, and their phases were identified using x-ray diffraction (XRD) coupled with a qualitative and quantitative analysis. Meanwhile, the band gap and electrical conductivity of each sample were characterised using UV-Vis DRS and LCRmeter, respectively. The FTIR spectrum identified the functional groups of Na-O, Fe-O, and Si-O, which are associated with the tetrahedral structure of NaO₄, FeO₄, and SiO₄. The XRD analysis reveals that the samples were dominated by Na₂FeSiO₄, followed by FeSiO₃ and SiO₂. The weight percent (wt.%) and unit cell volume of the Na₂FeSiO₄ phase tend to increase with an increasing temperature and change in both influences of their band gap and electrical conductivity. The band gap value tends to decrease with an increasing temperature, inversely proportional to the wt.% and unit cell volume, however, the electrical conductivity is opposite to their band gap value.