Effect of Cu2+ substitution on structural, magnetic and dielectric properties of cobalt ferrite with its enhanced antimicrobial property

Abstract

Cu2+ substituted cobalt ferrite represented chemically as Co1−xCuxFe2O4 (x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25) was prepared by the sol–gel assisted auto-combustion process using malic acid as a complexing agent. The auto-combusted sample was investigated using thermal analyzer, and accordingly, thermal treatments were given to the samples. The concentration of metal ions present was estimated using ICP-AES technique. Evaluation of transmission electron microscopy and scanning electron microscopy results indicate the homogenous distribution of particles along with agglomeration. X-ray photoelectron spectroscopy studies confirm the existence of elements in their respective oxidation states. Raman and Infrared spectroscopy were employed to shed light on the vibrational modes of the spinel ferrites. Magnetic properties determined from vibrating sample magnetometer at 50 K shows a significant increase in saturation magnetization (Ms) and coercivity (Hc) as compared to 300 K. While, the substitution of Cu2+ ions showed a marginal decrease in Ms and Hc at individual temperatures. The drop in Curie temperature (Tc) with Cu2+ content indicates the weakening in the strength of the overall A–B super-exchange interaction. The dielectric properties have been determined as a function of frequency and temperature. Antimicrobial tests performed, indicated that the Cu2+ content in CoFe2O4 significantly influenced the activity against both Gram-positive and Gram-negative pathogenic microbes.