Synthesis and characterization of hematite nanopowders

Abstract

A facile solution approach was employed to synthesize hematite (α-Fe2O3) nanoparticles by using starting precursor iron (III) chloride (FeCl3) and sodium hydroxide (NaOH) as reducing agent without templates at low temperature. The growth and solubility of iron oxide particle was controlled by adjusting the pH of the solution using ammonium hydroxide. As-prepared powders were subsequently calcined in air for 3 h at three different temperatures ranging from 400 to 800 °C. The precursor and the synthesized particles were characterized using TGA-DTA thermal analysis to study the decomposition pattern. X-ray diffraction (XRD) technique confirmed the nanocrystal formation of α-Fe2O3 and Fourier transform infra-red (FTIR) spectral information identified the metal-oxide phase formation. Scanning electron microscope (SEM) was engaged to study the morphology and the purity of the sample was evaluated from the energy dispersive spectrum (EDS). The optical band gap of the particles and its variations with calcination temperature (2.32–2.49 eV) was obtained from the constructed Tauc plot using the optical absorption data. The electrical parameters of the samples were obtained from two probe measuring technique and the effect of temperature on the electrical properties of α-Fe2O3 was discussed.