Electrical conductivity and magnetic properties of Li 0.5Fe 2.5− xCr xO 4 ferrite

Abstract

Cr-substituted lithium ferrite of different composition (Li 0.5Fe 2.5− x Cr x O 4) were prepared for x = 0.0–1.0 by conventional ceramic technique. A structure characterization of all the samples was carried out by the X-ray diffraction technique and found that the lattice parameter decreases with increasing of Cr-substituted concentration. Magnetic properties such as permeability and quality factor were measured in the frequency range of 1 kHz to 100 MHz. The permeability and quality factor of Cr-substituted lithium ferrite were strongly affected by Cr-substituted concentration. The permeability decreased gradually from μ ( f = 10 MHz) = 34.9 for Li 0.5Fe 2.5O 4 to μ ( f = 10 MHz) = 4.0 for Li 0.5Fe 1.5Cr 1.0O 4. The electrical conductivity and activation energy were measured by the DC two probes technique. The temperature dependence of DC conductivity shows the semiconductor nature. A change of slope in the Arrhenius plot (log σT vs. 10 3/ T) may be due to the ferri to paramagnetic transition. The conductivity variation shows two different regions with a large variation in the activation energy. The activation energies in the ferromagnetic region are greater than those in the paramagnetic region.