Microwave Sintering of Nanocrystalline Ni_1−xZn_xFe₂O₄ Ferrite Powder and Their Magnetic Properties

Abstract

Nanocrystalline Ni1−xZnxFe2O4 (0 ≤ x ≤ 1.0) powder with grain size of 30 nm was prepared using the spraying‐coprecipitation method. The obtained nanocrystalline Ni1−xZnxFe2O4 powder was sintered using conventional and microwave sintering techniques. The results show that the microstructure and magnetic properties of the sintered samples are obviously improved by microwave sintering of nanocrystalline Ni1−xZnxFe2O4 ferrite powder. The initial permeability of Ni1−xZnxFe2O4 ferrite increases with the increase in zinc concentration, although its resonance frequencies shift from high frequency to low frequency. The maximum initial permeability for microwave‐sintered Ni0.4Zn0.6Fe2O4 ceramic obtained at the temperature of 1170°C for 30 min reaches up to 360.9, and its resonance frequency is ~10 MHz. It may be attributed to the nanocrystalline Ni1−xZnxFe2O4 raw powder as well as the microwave sintering process, which results in a synergistic effect on improvement of the microstructure and magnetic properties.

Role of Microwave Sintering in the Preparation of Ferrites for High Frequency Applications

“…In Ni-Zn ferrites, the magnetic properties measurement show lower coercivity and higher magnetization for the microwave-sintered samples [68]. Th is may be due to contribution of microwaves to the uncoupling eff ect.…”

“…Th e lattice parameter was found to increase much slower with increasing zinc for the microwaveirradiated specimens. Mossbauer spectroscopy studies were performed at room temperature and the resonance lines are much sharper for the irradiated samples and indicating that a microwave-induced recrystallization of the ferrites [68][69]. Nanocrystalline Ni 1−x Zn x Fe 2 O 4 (0 ≤ x ≤ 1.0) powder with average grain size of 30 nm was prepared using the spraying-coprecipitation method.…”

“…Th e low dielectric constant observed in the microwave-sintered Ni-Zn sample suitable for high frequency applications [68][69]. Th e dielectric studies for NiCuZn-BT composites [91] show excellent properties such as ferromagnetic and ferroelectric when sintered in microwave conditions.…”

“…Surface of microwave-sintered pellets shows large pores but small in numbers whereas smaller pores and more in number for conventionally sintered composition[68].…”

Structural and Magnetic Properties of Hydrothermal Spinel Ni0.4Zn0.6Fe2O4 Ferrites

“…Gheisari et al 6 studied the nanocrystalline Ni 0.64 Zn 0.36 Fe 2 O 4 powders by high energy ball milling of ZnO, NiO and Fe 2 O 3 powders. Liu et al 7 prepared nanocrystalline Ni 1-x Zn x Fe 2 O 4 (0≤x≤1.0) powder with grain size of 30 nm using the spraying-coprecipitation method, and the microstructure and magnetic properties of samples after the conventional and microwave sintering were studied. Gabal et al 8 found that egg-white precursor method provided a simple and cost-effective route to synthesize single phase Ni 1-x Zn x Fe 2 O 4 (x=0.0-1.0) nanopowders.…”