Preparation and studies of electrical properties of cobalt substituted Li-Zn ferrites by sol-gel auto combustion method

A series of Co substituted lithium zinc ferrite powders with different content of Co (0.00 to 0.1 in steps of 0.02) were prepared by a novel sol-gel auto combustion process using citric acid. Their spinel structure was confirmed by XRD. The variation in lattice parameter and density with cobalt concentration was studied which showed an increasing trend. A decreasing pattern was observed in variation of porosity with increasing Co. Room temperature dielectric constant and resistivity were studied as a function of composition at 10 KHz. The room temperature dielectric constant decreases with successive addition of Co2+ in the series. The observed variation in dielectric constant has been explained on the basis of space charge polarization and Koops two layer model. Resistivity is observed to increase with increasing concentration and the observed variation in resistivity has been explained by Verwey hopping mechanism.Author Affiliation: Ibetombi Soibam1, Sumitra Phanjoubam1, H B Sharma1, H N K Sarma1 and Chandra Prakash2 1Department of Physics, Manipur University, Canchipur, Imphal-795 003, Manipur, India 2Directorate of ER & IPR, DRDO Bhawan, Rajaji Marg, New Delhi-110 011, India E-mail : [email protected] of Physics, Manipur University, Canchipur, Imphal-795 003, Manipur, India 2Directorate of ER & IPR, DRDO Bhawan, Rajaji Marg, New Delhi-110 011, Indi

Improved Properties of Li-Mn-Ti Ferrites by Microwave Sintering

Substituted Li-ferrites are attractive materials for research due to their important properties like high Curie temperature leading to high thermal stability, high and wide range of saturation magnetization, low stress sensitivity of remanence and they are very good dielectric materials. The properties are very sensitive to the type and amount of substituents, method of preparation and sintering conditions. Attempts to minimize loss of lithia and oxygen during sintering by adopting various processing method, which otherwise is very difficult to control technologically by conventional method, has been a continuous efforts for the researchers.The present paper reports the improvements that arise in the properties of Li-Mn-Ti ferrite by using novel microwave (MW) processing technique. Mn4+ and Ti4+ substituted Li-ferrites having the compositional formula Li0.60Mn0.1Ti0.1Fe2.20O4 were prepared by both the conventional and microwave techniques. XRD confirmed the formation of single phase with spinel structures in both the samples. Dielectric properties were studied as a function of temperature. Dielectric properties of MW processed sample were found to be more stable with temperature. Significant improvement in the d. c. resistivity was observed in theMWsintered sample over the conventional sintered sample. The possiblemechanisms involved are discussed

Influence of temperature on the dielectric behaviour of Co²⁺ substituted Li-Ni-Mn ferrites

199-202Li-Ni-Mn ferrites substituted with Co²⁺ having compositional formula Li₀․₄₅₋x/₂Ni₀․₁Mn₀․₁CoxFe₂․₃₅₋x/₂O₄ with x ranging from 0 to 0.1 in steps of 0.02 were prepared by the conventional ceramic technique. The temperature dependence of the dielectric constant and loss tangent have been investigated. The dielectric constant increased with the increase of temperature, the increase being more pronounced at lower frequencies indicating the dominant role played by the interfacial polarisation. Dielectric constant studied as a function of temperature showed peaks, which gets shifted to higher temperature as the frequency increased. The dielectric loss tangent was observed to increase with temperature. The results obtained are explained on the basis of Debye’s equation