Structural, morphological and electrical properties of α-Fe2O3 nanoparticles prepared by chemical route

Abstract

In this work, hematite α-Fe₂O₃ nanoparticles were synthesized by the chemical route technique. X-ray diffraction measurements confirmed the existence of a hematite phase with rhombohedral crystal structure upon calcination of as-synthesized goethite α-FeO(OH) at 600, 700, and 800 °C. The average crystallite size increased from 11.4 nm to 20.6 nm, while microstrain decreased from 2.27 × 10⁻³ to 1.25 × 10⁻³ with increasing calcination temperatures. Scanning electron microscopy micrographs and dynamic light scattering measurements revealed spherical nanoparticles with particle size distribution ranging from 200 nm to 500 nm. Fourier transform infrared spectroscopy spectra confirmed the existence of Fe-O and O-H bonds. The dielectric measurements in the frequency range from 100 Hz to 100 MHz exhibited extremely high dielectric constants ∼10⁹ at low frequencies and were found to increase with increasing calcination temperatures. Empirical models were proposed to estimate dielectric constants as a function of calcination temperature and crystallite size with excellent coincidence with the experimental data.