Electrical properties of bismuth doped CoBixFe2-xO4 nano ferrites

Abstract

The CoBixFe2-xO4 (x = 0.00, 0.05, 0.10, 0.15, 0.20 & 0.25) nano ferrites have been synthesized by sol-gel combustion method. The prepared samples were calcinated at 600°C for 5 hrs. The structural and morphological properties of all prepared samples were characterized by X-ray diffraction (XRD). The effect of bismuth ion substitution on cobalt ferrite samples clearly show fcc spinal structure and confirms the particle size ranges within 17-26 nm. It is also observed that the lattice parameters were decrease in trend with increase of bismuth ion concentration. These samples further characterized the electrical properties by using two-probe type method within the temperature range 300 to 973 K. It is also verified that the electrical conductivity is decreasing with increase of Bi3+ ion concentration. This is the fact that the hopping of electrons decreases in between Fe2+ - Fe3+ ions and samples exhibit semi conducting nature. Further the values of activation energy (ΔE) and Curie temperature (Tc) were determined from the graph of variation of DC electrical resistivity with temperature. As a function of frequency the dielectric properties were measured at room temperature in the range 20Hz to 2MHz. The dielectric properties such as dielectric constant (ε’), dielectric loss tangent (tan δ) and AC conductivity (σAC) were exhibiting normal ferrite behavior as a function of applied frequency. It has been observed that both the dielectric constant and dielectric loss tangent were decreases with the increase of frequency whereas the AC conductivity was increasing in trend with the increase of doping concentration as well.