Influence of reduction temperature on composition, particle size, and magnetic properties of CoFe alloy nanomaterials derived from layered double hydroxide precursors

Abstract

Individual CoFe alloy nanoparticles and CoFe–MgO nanocomposites were prepared through thermal reduction of single-source layered double hydroxide (LDH) precursors at various temperatures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analyses to investigate the influence of reduction temperature on the composition, particle size and size distribution, as well as the magnetic properties of the resulting materials. XRD and SEM results show that the as-prepared CoFe alloy nanoparticles and CoFe–MgO nanocomposites display high crystallinity and high purity. The average particle size of individual CoFe nanoparticles increases with the increase of reduction temperature. In the presence of the MgO matrix, uniform CoFe alloy nanoparticles with a narrow diameter distribution (8–11 nm) were obtained. Magnetic measurements indicate that the saturation magnetization strength (M_s) of the resulting materials increases with reduction temperature. The individual CoFe alloy nanoparticles exhibit excellent soft magnetic behavior with an extremely high M_s value (213 emu g⁻¹ at 800 °C), comparable to that of bulk CoFe alloy (230 emu g⁻¹). For CoFe–MgO nanocomposites, small M_s values were obtained due to the small CoFe alloy particle size and low percentage of magnetic component. However, the coercivities are greatly enhanced (663 Oe at 450 °C) for the composites, implying their potential applications in data storage and other magnetic devices.