Comparison of Preparation Techniques of Cobalt Nano ferrites and their Characterization

Abstract

Cobalt ferrite nanoparticles were successfully synthesized using sol-gel and the chemical coprecipitation methods. In sol-gel method nitrates of cobalt and iron was used. Citric acid was used as chelating agent and ammonia was used to maintain the pH at 7. Sample S1 was synthesized by sol-gel method.In chemical co-precipitation technique nitrates of cobalt and iron was used. Sodium hydroxide (NaOH) was used as a precipitant agent.Three different samples S2, S3 and S4 were synthesized using different molarity of the precipitant agent. All the samples were heat treated at 9000C. Structural and morphological properties were investigated using XRD, SEM and EDS techniques.XRD results confirmed the formation of the spinal structure of the cobalt nanoferrites for each of the sample. Average crystallite size for sample S1, S2, S3 and S4 are 53.5nm, 21.5 nm, 35.5 nm and 35.5 nm respectively. SEM micrograph images confirmed thepresence of the nanostructured cobalt ferrite nanoparticles.EDS patterns showed the compositional purity of each of the sample. Calculated density is compared with the theoretical density. Electrical and dielectric properties were also measured for all the samples. Variation in the values of dielectric constant, dielectric loss and ac conductivity were measured in the range of frequencies from 100 Hz to 5 MHz. DC conductivity andac conductivity was determined from this data. Results showed that cobalt ferrite synthesized by the sol-gel method had the greater value of resistivity and smaller values of dielectric constant and dielectric loss as compared to the sample prepared by the chemical co-precipitation method. So these materials can be used for the high frequency applications.