Structural and Optical Properties of Fe Doped Tio<sub>2</sub> Nanoparticles: Investigation of Effects of Different Doping Concentration

Abstract

Fe-doped TiO<sub>2</sub> nanoparticles (F-T NPs) were synthesized using the sol-gel method where different molar concentrations (0, 1, 2, 3, 5, 7, 9, and 10%) of Iron (iii) nitrate were added to a constant amount of the metal precursor TetraisopropylOrthotitanate (TTIP) solution, the solvent precursor ethanol and refluxing agent diethanolamine at the ratios of 1:6:1 respectively. The gel formed was annealed at 500°C in a muffle furnace for 2h. Fourier Transform Infrared (FTIR) showed Fe-O symmetrical stretching vibration for the 5% doping and above and Ti-O-Fe asymmetrical stretching vibration at wavenumber 668 cm<sup>-1</sup> and 1033cm<sup>-1</sup>, respectively. Fe-O stretching vibration confirms substitution doping. The crystallite size was calculated using the Debye Scherer equation; 2% F-T NPs had the largest crystallite size at 16.45 nm, and 7% F-T NPs had the least size at 10.95 nm, a decrease of 2.80 nm from the 0% F-T NPs. X-ray diffraction spectra showed a merging of peaks at planes 105 and 211. The peak at plane 204 is found to diminish, and the growth of another peak at 2θ (64.28°). Optical analysis was studied using UV-Vis, where the Tauc plot estimated the calculated band gap (E<sub>g</sub>). It was the least at 7% F-T NPs with a value of 4.41 eV, and 5% F-T NPs were found to have the highest value of 4.86 eV.% Transmittance is directly proportional to the optical band gap. Scanning Electron Microscope showed improved agglomeration and aggregation with a dense and smooth particle. Energy Dispersive Spectroscopy confirmed the presence of Fe, Ti, and O in the F-T NPs.