Magnetic characteristics and hyperthermia properties of copper-cobalt ferrite (CuxCo1−xFe2O4) nanoparticles

Abstract

The specific properties of magnetic ferrites have made them a point of interest in magnetic field hyperthermia studies. However, magnetic characteristics and hyperthermia properties of copper-cobalt ferrite nanoparticles (NPs) with different compositions have received little attention. Here, CuxCo1−xFe2O4 (0 ≤ x ≤ 1) NPs are synthesized via a simple chemical co-precipitation method at a temperature of 80 °C. The Cu substitution causes the crystallite size and average size of the NPs to show decreasing trends, affecting the corresponding magnetic parameters such as saturation magnetization (Ms) and coercivity (Hc), as well as hyperthermia properties. By increasing x from 0 to 1, hysteresis loop results show that Ms and Hc decrease from 65.3 to 11.7 emu/g and 95.8 to 1.4 Oe, respectively, arising from the complete replacement of Co2+ ions by Cu2+ ones. First-order reversal curve (FORC) analysis is employed to investigate magnetic characteristics of the NPs, revealing enhancements in the superparamagnetic fraction up to 83% with increasing the Cu content. Hyperthermia measurements (H = 400 Oe and f = 400 kHz) of pure Co and Cu substituted Co ferrite NP ferrofluids prepared in a water medium show a continuous reduction in specific loss power (SLP) when increasing x. In this case, SLP of Cu0.2Co0.8Fe2O4 NPs with a wide FORC coercive field distribution is found to increase from 67.6 to 108.6 W/g with decreasing the ferrofluid concentration from 7 to 5 mg/ml, indicating the effective role of Neel and Brownian relaxations in the heating efficiency.