Synthesis and characterization of hematite (α-Fe₂O₃) nanoparticles

Abstract

Hematite (α-Fe2O3) nanoparticles were successfully synthesized from 2-line ferrihydrite precursor via a simple chemical precipitation method by using sodium hydroxide as a precipitating agent, with trace amounts of Fe (II) as a catalyst, and under nitrogen atmosphere. The influences of the synthesis conditions, such as the precursor concentration, the solution pH, the amount of catalyst on the size and morphology of the hematite particles were systematically investigated. The structure and morphology of the synthesized hematite particles were characterized by XRD, FT-IR, TG/DTA, and FE-SEM. Moreover, the electrical and magnetic properties were studied by using an electrometer with a custom-built two-point probe and a vibrating sample magnetometer (VSM), respectively. The results indicate that the synthesized products fabricated at pH 5-9 and at temperatures between 60-100 ℃ for 1h are of a single phase of the hexagonal structure hematite without any other impurities. The physical morphology of the synthesized hematite appears to be composed of a large number of very small particles which can be called as the “raspberry shape”. Particle size and shape of the synthesized hematite can be easily controlled by adjusting the synthesis conditions. The particle size of the synthesized hematite can be successfully controlled to be in the range of 50-150 nm. Different morphologies consisting of the spherical-like, the cubic-like, and the ellipsoidal particles are also obtained by using the present synthesis method. Different particle sizes and shapes of the synthesized hematite are shown to critically affect the electrical and magnetic properties.