Effect of Fe3+ ions substitution on electrical and dielectric properties of MgFexCr2-xO4 (x = 0, 0.2, and 0.4 mol%) chromites prepared by solution combustion method

Abstract

This paper reports the structural, dielectric and electrical properties of Fe3+ ions substituted magnesium chromite with composition MgFexCr2-xO4 (x = 0, 0.2, and 0.4 mol%) synthesized via solution combustion method. The structural analysis was done by XRD pattern which confirmed the formation of cubic crystal symmetry of the samples with Fd-3 m space group. The value of lattice parameters of MgFexCr2-xO4 chromites slightly increased with increasing concentration of Fe3+ ions. The TEM (Transmission electron microscopy) micrographs at different magnifications showed the spherical particles of the sample and average particle size was found to be ≈ 56.22 nm. The dielectric parameters (dielectric constant and dielectric loss) and ac conductivity were investigated in the frequency range of 100 Hz–100 kHz and temperature range of 50 °C–350 °C. The dielectric studies showed that the dielectric parameter decreases in high frequency range which can be explained by Maxwell-Wagner type of space charge polarization. The dielectric constant increases with increasing concentration of Fe3+ ions due to increase in polarization. The frequency and temperature dependent ac conductivity was studied and found that the conductivity value increases with an increase in frequency and temperature, which followed the Jonscher's universal power law. The ac conductivity decreases with increasing Fe3+ ions due to formation of grain boundary defect barrier. The non-Debye type relaxation behavior of the MgFexCr2-xO4 samples was confirmed by the Cole-Cole plot. The obtained result shows the capability of magnesium chromite for fabrication of micro-electronic devices, sensors, and other electronic devices.