• Korean Journal of Crystallography
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• v.12 no.2
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• pp.70-75
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• 2001

The purpose of this study is to investigate the effect of V₂O/sub 5/ addition on physical and magnetic properties of NiCuZn ferrite for multi-layer chip inductors. NiCuZn ferrite pastes doped with 0, 0.1, 0.3 and 0.5 wt% V₂O/sub 5/ were prepared and samples of ferrite sheets were prepared by the screen printing method. They were sintered at 870, 880, 890 and 900℃, and then their physical and magnetic properties were analyzed. After sintering at 870℃, the sintered density of the ferrite sheet doped with 0.5wt% V₂O/sub 5/ showed the highest value to 5.08g/cm³due to the best densification by the liquid phase sintering, while the microstructures of ferrite sheets doped with 0.1 and 0.3 wt% V₂O/sub 5/ showed and inhibited grain growth. Irrespective of the sintering temperature, the initial permeability of ferrite sheet doped with 0.5 wt% V₂O/sub 5/ was highest and after sintering beyond 880℃, the quality factor of 0.3 wt% V₂O/sub 5/-doped sample appeared to be highest.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.226-231
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• 2020

Polyvinyl pyrrolidone nanofibers including nickel, zinc, and iron precursors were fabricated via the electrospinning method. To convert as-spun nanofibers to Ni0.5Zn0.5Fe2O4 oxide nanof ibers which is capable of shielding an electromagnetic wave, heat treatment conditions were optimized. To obtain the heat treatment condition that can exclude amorphous carbon black and secondary crystal phase, samples were taken at each temperature while the calcination process and analyzed. According to the X-ray diffraction (XRD) analysis, the Ni0.5Zn0.5Fe2O4 crystal phase started to appear from 300℃, but it was confirmed through energy dispersive spectroscopy (EDS) analysis that heat treatment of 500℃ or more was required to remove most of the carbon black. When the calcination temperature exceeds 650℃, crystal nuclei starts to grow and the fiber surface condition becomes rough, so it was confirmed that the heat treatment conditions should be selectively determined according to the application field.

• Journal of the Korean Magnetics Society
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• v.16 no.4
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• pp.201-205
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• 2006

The electromagnetic properties and microstructure of the basic composition of $(Ni_{0.2}Cu_{0.2}ZnO_{0.2})_{1.02}(Fe_{2}O_{3})_{0.98}$ were invested, changing the amount of the additives $Bi_2O_3$ and $ZrO_2$ and sintering temperature. The spinel structure of specimen was confirmed by the analysis of XRD patterns. Grain size and its density are increased by increasing the additive and the sintering temperature.However, the permeability increased with decreasing additive. It was also found that $Bi_2O_3$ had more effect on the increase of grain size and permeability rather than $ZrO_2$.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 1997.11a
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• pp.15-75
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• 1997

• Proceedings of the Korean Vacuum Society Conference
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• 1992.02a
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• pp.87-88
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• 1992

• Journal of Navigation and Port Research
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• v.30 no.9
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• pp.767-772
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• 2006

Generally, a silicone rubber and a chlorinated polyethylene(CPE) have been used as a binder for the development of high-performance composite EM(Electro Magnetic) wave absorbers. In this paper, the EM wave absorption performance of natural lacquer, which is newly proposed as a binder was investigated. The prepared MnZn ferrite EM wave absorbers are mixed with natural lacquer showed excellent EM wave absorption characteristics compared with MnZn ferrite EM wave absorbers which are mixed with the conventional binders. MnZn ferrite EM wave absorbers mixed with natural lacquer were prepared and their absorption ability was also investigated The EM wave absorbers are fabricated in different proportions of MnZn, or NiZn ferrite and natural lacquer, and their reflection coefficients are measured. The permittivity and permeability are calculated by using the measured reflection coefficients. The EM wave absorption abilities are calculated according to different thicknesses of the EM wave absorbers.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.157-161
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• 2006

Generally, a silicone rubber and a chlorinated polyethylene(CPE) have been used as a binder for the development of high-performance composite EM(Electro Magnetic) wave absorbers. In this paper, the EM wave absorption performance of natural lacquer, which is newly proposed as a binder was investigated. The prepared MnZn ferrite EM wave absorbers are mixed with natural lacquer showed excellent EM wave absorption characteristics compared with MnZn ferrite EM wave absorbers which are mixed with the conventional binders. MnZn ferrite EM wave absorbers mixed with natural lacquer were prepared and their absorption ability was also investigated. The EM wave absorbers are fabricated in different proportions of MnZn, or NiZn ferrite and natural lacquer, and their reflection coefficients are measured. The permittivity and permeability are calculated by using the measured reflection coefficients. The EM wave absorption abilities are calculated according to different thicknesses of the EM wave absorbers.

• Journal of the Korean Magnetics Society
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• v.6 no.6
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• pp.382-387
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• 1996

The characteristics of the complex permeability of ${(Ni_{x}Cu_{0.2}Zn_{0.8-x}O)}_{1-w}{(Fe_{2}O_{3})}_{1+w}$ with various Ni and $Co_{3}O_{4}$ contents were investigated in this work. It is found that the NiCuZn ferrites with $x{\geq}0.6$ have a relatively small peak width of the imaginary part of permeability $\mu$". The resonance frequency is increased as Ni content becomes higher, where the loss is low. The $\mu$" value decreases with increasing FezO, deficiency, but the resonance frequency($f_{\mu"max}$) is only slightly affected by $Fe_{2}O_{3}$ deficiency. In case of $Co_{3}O_{4}$ addition to the NiCuZn ferrites, the $f_{\mu"max}$ increases since the initial permeability decreases with the amount of $Co_{3}O_{4}$. It is concluded that the Ni content in the NiCuZn ferrite is a dominant factor for the total loss of these spinel ferrites.

• Journal of Magnetics
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• v.18 no.4
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• pp.391-394
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• 2013

In this study, nickel-zinc ferrite nanoparticles, with the chemical formula of $Ni_{0.3}Zn_{0.7-x}Cu_xFe_2O_4$ (where x = 0.1- 0.6 by step 0.1), were fabricated by the sol-gel method. The effect of copper substitution on the phase formation and crystal structure of the sample was investigated by X-ray diffraction (XRD), thermo-gravimetry (TG), differential thermal analysis (DTA), Fourier transform infrared spectrometry (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD result shows that due to the reduction of Zn content,the crystallite size of the sample increased. The results of the vibration sample magnetometer (VSM) exhibit an increase in saturation magnetization value (Ms) for samples with x ${\leq}$ 0.3 and a linear decrease for samples with x > 0.3. The variation of saturation magnetization and coercivity of the samples were then studied.

• Journal of the Korean Magnetics Society
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• v.13 no.1
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• pp.15-20
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• 2003

Diffusion speed of Cu metal fine particle is fast better than CuO, so it will promote grain growth in sintering. In this paper, the influence on substituting Cu fine particle for CuO of NiCuZn ferrite with basic composition (N $i_{0.204}$C $u_{0.204}$Z $n_{0.612}$ $O_{1.02}$)F $e_{1.98}$ $O_{2.98}$ has been investigated with varying Cu/CuO ratio. The perfect spinel structure of sintered specimen at 90$0^{\circ}C$ was confirmed by the analysis of XRD patterns. The best condition was obtained when the ratio of Cu/CuO was 60%, and the permeability was 1100 and Ms was 87 emu/g in this condition. Cu has influenced on grain growth in sintering, substituting Cu fine particle for CuO could lower sintering temperature over the 3$0^{\circ}C$. After sintering, substituting Cu performed as good as CuO.s CuO.s CuO.