Search

Nickel‐copper‐zinc (NiCuZn) spinel ferrites have attracted intensive research owing to their unique magnetic properties and low co‐fire temperature. Combustion synthesis has been viewed as a promising protocol for the large‐scale fabrication of NiCuZn spinel ferrites. However, the spinel ferrites prepared by this method usually suffer from limited saturation magnetization and high coercivity due to their large size, which will impose detrimental harmonics on electrical equipment (e. g. transformer, motor, etc.). To address these issues, highly porous NiCuZn spinel ferrite hierarchies were prepared within several hours through a modified solution combustion method, using glucose and ammonium nitrate as the fuel and combustion enhancer, respectively. The as‐obtained NiCuZn spinel ferrite hierarchies show excellent magnetic properties with a high saturation magnetization up to 62.61 emu/g and a low coercivity of 9.6 Oe thanks to the rational distribution of cations and grain size. More importantly, this method also allows various modifications (heteroatom doping) and large‐scale applications, which may be promising for the fabrication of high‐performance soft magnets for electrical equipment. [ABSTRACT FROM AUTHOR]

Spinel ferrites have been widely used in various fields, among which nickel‐zinc (NiZn) ferrites have drawn much attention due to their high electrical resistivity as well as low eddy current loss. To accommodate highly‐integrated modern electronic devices, the preparation methods for nano/micro‐sized NiZn ferrites have been widely discussed. Nevertheless, these current synthesis routes are usually cost/time‐consuming, which hinders their large‐scale production for practical applications. Herein, we present a facile, low‐cost synthesis strategy for NiZn ferrites (NixZn1−xFe2O4, x=0, 0.25, 0.5, 0.75 and 1) through a blowing‐combustion method. The effect of Ni/Zn molar concentration on the structure, morphology as well as magnetic properties has been thoroughly investigated through X‐ray diffraction, Raman spectroscopy, scanning electron microscopy and vibrating sample magnetometer. Thanks to the synergetic effect of the pure phase and moderate Ni molar concentration, the Ni0.75Zn0.25Fe2O4 shows an enhanced saturation magnetization of 44.98 emu/g. More importantly, this blowing‐combustion method may also be commonly applied to other spinel ferrites with different stoichiometric ratios and heteroatom doping. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nickel-copper-zinc (NiCuZn) ferrites were prepared by a facile blowing-combustion method. • Variation of zinc content with temperature was investigated through inductive coupled plasma (ICP). • The effect of sintering temperatures on structural and magnetic properties of NiCuZn ferrites were investigated. We report the fabrication of nickel-copper-zinc (NiCuZn) ferrites via a facile blowing-combustion method, where the grain size and morphology can be readily controlled by adjusting the sintering temperature. The effect of sintering temperatures on the structural evolution as well as the magnetic properties of the NiCuZn ferrites was systematically studied. It's found that the Zn elemental content is highly dependent on the sintering temperature and would undergo evaporation when annealing at 800 °C, which consequently greatly affects the magnetic properties of NiCuZn ferrites. [ABSTRACT FROM AUTHOR]