Structural and electrical properties of Ni1-xMgxFe2O4 synthesized by citrate gel process

The structural and electrical properties of magnesium-substituted nickel ferrite having the general formula of Ni1-xMgxFe2O4 (x=0, 0.3, 0.6, 0.9) has been studied as a function of magnesium ion concentration. The materials have been prepared by citrate gel process using metal nitrate salts as a cation precursors and citric acid as gelating agent. The powder X-ray diffraction pattern confirms fcc structure for the synthesized compound. The variation of lattice parameter and the tetrahedral radius increases with increase in Mg2+ ion concentration. The AC electrical parameters such as dielectric constant (ε') and loss tangent (tan δ) for all the systems have been studied as a function of frequency in the range 50 Hz to 10 kHz at room temperature. A maximum DC electrical conductivity of 3.3 S cm-1 was obtained at a temperature of 1000 deg. C and a AC electrical conductivity of 10.94x10-6at 10 kHz was observed in the composition x=0.6 i.e. for Ni0.4Mg0.6Fe2O4 compound which may be due to the maximum Fe2+ concentration in the octahedral sites. The dielectric constant follows the Maxwell's-Wagner interfacial polarization and the relaxation peaks were observed in the dielectric loss properties. The FTIR spectra show the characteristic peaks of ferrite sample. The morphological features were studied using scanning electron microscope