Indian J. Phys. 83 (3), 285-290 (2009) © 2009 IACS Preparation and studies of electrical properties of cobalt substituted Li-Zn ferrites by sol-gel auto combustion method Ibetombi Soibam 1 , Sumitra Phanjoubam 1 , H B Sharma 1 , H N K Sarma 1 and Chandra Prakash 2 1 Department of Physics, Manipur University, Canchipur, Imphal-795 003, Manipur, India 2 Directorate of ER & IPR, DRDO Bhawan, Rajaji Marg, New Delhi-110 011, India E-mail : ibetombi_phys@rediffimail.com Received 18 June 2008, accepted 29 September 2008 Abstract : 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 Co 2+ 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. Keywords : Spinel phase, electrical, sol-gel, fine particles PACS Nos. : 78.67.Bf, 72.15.Eb 1. Introduction Ferrites represent an important category of materials, which are in great demand due to their numerous practical applications. Lithium and substituted lithium ferrite are among them and are gaining importance because of their technological applications ranging from microwave to radio frequency. The electrical and magnetic properties of ferrites are strongly dependent on their chemical composition and their method of preparation in general [1-3]. One of the most popular nonconventional synthesis method used in the solgel auto * Corresponding Author