Electrospinning synthesis of shuttle-shaped NiCuZn ferrites and effect of sintering temperature on their structural and magnetic properties

Nickel-copper-zinc (NiCuZn) ferrites are widely used in high-frequency fields due to their low eddy current losses as well as high resistivity, but which are greatly affected by their microstructures, such as porosity, grain size. Herein, we report a novel synthesis of shuttle-shaped NiCuZn ferrites through electrospinning and subsequent sintering. The microstructural evolution and its effect on magnetic properties upon annealing at temperatures ranging from 500 to 1000 °C are systematically investigated through X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and vibrating sample magnetometry. The results demonstrate that the average crystallite size of NiCuZn ferrites decreases and the grain size rises with increasing the sintering temperature. Meanwhile, the saturation magnetization shows an upward trend upon increasing the sintering temperature and reaches the highest value of 68.07 emu g⁻¹ at 900 °C. However, when further increasing the sintering temperature to 1000 °C, the crystalline structure, as well as the morphology of the NiCuZn ferrite, change a lot with coarse particle growth/aggregation, thus resulting in lowered saturation magnetization. Inductively coupled plasma mass spectrometer analysis shows that the stoichiometric ratios of NiCuZn ferrite change with the sintering temperature, which also affects the magnetic properties. More importantly, this study demonstrates that electrospinning is promising to fabricate well-defined nanostructured ferrites with tunable components, morphologies, and magnetic properties.