Combustion synthesis of nanosized γ-Fe₂O₃: Structural, electrical, dielectric and magnetic studies

Abstract

Combustion synthesis of nanosized γ-Fe₂O₃ using polyethylene glycol as a fuel has been reponed. Four different precursors were taken to see the feasibility of conversion to γ-Fe₂O₃ in a single step. The as synthesised γ-Fe₂O₃ samples were characterised by X-ray diffraction (XRD), infrared (IR), transmission electron microscopy (TEM), electrical, dielectric,

magnetic and Mossbauer techniques. The γ-Fe₂O₃ samples were found to crystallise in a cubic system. Unit cell parameters were obtained by least square refinement of the X-ray powder data using PROZSKI program. The crystallite sizes were calculated using X-ray line broadening. TEM studies showed that particles are in the range of 20-50 nm. X-ray, tap and

apparent densities were determined and compared with the γ-Fe₂O₃ prepared by conventional methods. All the γ-Fe₂O₃ samples showed semiconducting behaviour. From dielectric studies it was observed that dielectric constant vary from 100 to 2000 depending upon the precursor used to prepare γ-Fe₂O₃ and number of Fe²⁺ and Fe³⁺ ions present in that sample. The saturation magnetisation of these samples are in the range of 40-50 emu/g.