Structural, morphological and dielectric investigation of spinel chromite (XCr2O4, X = Zn, Mn, Cu & Fe) nanoparticles

The nature of engineering technique has a significant effect on the particle size, particle distribution and thus affects the morphological, electrical and dielectric properties of the materials. In this work, ZnCr2O4, MnCr2O4, CuCr2O4 and FeCr2O4 nanoparticles have been synthesized using wet chemical based sol–gel auto-combustion method. The crystal structure, lattice constant, unit cell volume, X-ray density and porosity of the calcined powder samples were determined from the data obtained from X-ray diffractometer. Morphology, grains size and distribution of the grains were analyzed using field emission scanning electron microscopy. Dielectric response of the samples was checked in the frequency range of 20 Hz to 20 MHz. The analysis of real and imaginary dielectric constant and tangent loss revealed a non-linear dielectric behavior of the spinel oxides. A strong frequency dependent response of different electroactive regions was found by impedance spectroscopy. Hopping of charge carriers in the conduction mechanism of spinel chromites was analyzed from the variation of ac conductivity with frequency.