Synthesis and studies on magnetic properties of single-phase cobalt ferrite nanoparticles: influence of content of chelating agent

Abstract

A systematic investigation has been carried out to achieve and characterize single-domain cobalt ferrite nanoparticles of high saturation magnetization with least particle size. The samples were obtained by adding different contents of chelating agent, viz., polyvinylpyrrolidone, to cobalt ferrite in the ratios 1:1–3:1 and with careful heat treatment using sol–gel technique. The ferrite samples were annealed in the temperature range 400–1100 °C in the intervals of 100 °C for achieving crystallization to the nanoscale. The prepared samples were characterized by XRD and TEM techniques to identify single-phase spinel structure and the particle size. The magnetic properties, viz., saturation magnetization (Ms), coercivity (Hc) and single-domain nature of the samples, were measured using vibrating sample magnetometer. The obtained results have been discussed in detail as a function of the content of chelating agent. The analysis indicated the developed samples are of single-domain cobalt ferrite nanoparticles with a critical size of 12.8 nm, possess high saturation magnetization (71.9 emu/g) and high coercivity (2744 Oe).