Electrical and Magnetic Studies of Maghemite (γ-Fe2O3) Prepared by the Sol-Gel Route

Maghemite (gamma-Fe2O3) nanopowder was prepared by the sol-gel method. The microstructural and morphological properties of the prepared sample were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrical investigation was performed by impedance spectroscopy and the temperature/magnetic field dependence of magnetization was investigated using a magnetometer. The characterization results confirmed that the reflection peaks indexed by XRD correspond to the gamma-Fe2O3 material with a crystallite size of 8 nm. The nanoparticles of the sample we prepared present a spherical shape and small size with high porosity. The electrical conductivity is in good agreement with Jonscher's law. Consequently, the displacement of charge carriers corresponds to the pattern of correlated barrier jumps over the dispersive region generated by interstitial defects and vacancies. The Nyquist diagram shows the presence of grains and grain boundary effects on the electrical transport in the structure of our material. The dielectric behavior was correlated with the polarization effect and a small dielectric loss. The saturation magnetization shows a high value for our sample, corresponding to 57 emu/g at room temperature (300 K) and 65 emu/g at a temperature of 5 K.