• 마이크로전자및패키징학회지
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• 제22권3호
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• pp.45-50
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• 2015

Glycine-nitrate와 citric acid를 이용하여 단상의 Ni-Zn ferrite, Ba-ferrite 나노입자와 두 나노복합체 ferrite의 전구체를 제조하고 이를 열처리하여 XRD 및 FT-IR로 각각의 상 분석을, SEM으로 분말의 형상과 크기를, VSM으로 자기적 특성과 합성된 나노복합체 ferrite에서의 exchange-coupling 상호작용을 확인하였다. XRD 분석 결과, 자전 연소법으로 얻은 전구체로 단상의 Ni-Zn ferrite와 Ba-ferrite 나노 입자 및 $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ 나노복합체 페라이트가 합성되었으며, 나노복합체에는 $BaFe_{12}O_{19}$와 $Ni_{0.5}Zn_{0.5}Fe_2O_4$가 잘 분포되어 있어 경자성과 연자성이 공존하고 있음을 확인하였고, 나노복합체 페라이트의 히스테리시스 곡선의 형상을 통해 경자성과 연자성 사이에 exchange-copuling이 잘 이루어졌음을 확인할 수 있었다. VSM으로 측정한 나노복합체의 경우. GNP로 제조한 precursor를 $900^{\circ}C$에서 하소한 $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ 나노복합체는 포화자화 81.69 emu/g, 잔류자화 38 emu/g, 보자력 2598.48G를 나타내었다. $Ni_{0.5}Zn_{0.5}Fe_2O_4/BaFe_{12}O_{19}$ 복합체에서 $BaFe_{12}O_{19}$의 무게비가 증가 할수록 보자력은 증가하였고, 포화자화값과 잔류자화 값은 감소하였다.

• 한국세라믹학회지
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• 제50권3호
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• pp.231-237
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• 2013

Thermodynamic modeling of the $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ complex ferrite system has been adopted as a rational approach to establish routes to better synthesis conditions for pure phase $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ complex ferrite. Quantitative analysis of the different reaction equilibria involved in the precipitation of $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ from aqueous solutions has been used to determine the optimum synthesis conditions. The spinel ferrites, such as magnetite and substitutes for magnetite, with the general formula $MFe_2O_4$, where M= $Fe^{2+}$, $Co^{2+}$, and $Ni^{2+}$ are prepared by coprecipitation of $Fe^{3+}$ and $M^{2+}$ ions with a stoichiometry of $M^{2+}/Fe^{3+}$= 0.5. The average particle size of the as synthesized $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$, measured by transmission electron microscopy (TEM), is 14.2 nm, with a standard deviation of 3.5 nm the size when calculated using X-ray diffraction (XRD) is 16 nm. When $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ ferrite is annealed at elevated temperature, larger grains are formed by the necking and mass transport between the $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ ferrite nanoparticles. Thus, the grain sizes of the $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ gradually increase as heat treatment temperature increases. Based on the results of Thermogravimetric Analysis (TGA) and Differential Scanning Calorimeter (DSC) analysis, it is found that the hydroxyl groups on the surface of the as synthesized ferrite nanoparticles finally decompose to $Ni_{0.5}Zn_{0.4}Cu_{0.1}Fe_2O_4$ crystal with heat treatment. The results of XRD and TEM confirmed the nanoscale dimensions and spinel structure of the samples.

• Carbon letters
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• 제24권
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• pp.103-110
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• 2017

Carbon-based magnetic nanostructures in several instances have resulted in improved physicochemical and catalytic properties when compared to multi-wall carbon nanotubes (MWCNTs) and magnetic nanoparticles. In this study, magnetic MWCNTs with a structure of $Ni_xZn_xFe_2O_4/MWCNT$ as peroxidase mimics were fabricated by the one-pot hydrothermal method. The structure, composition and morphology of the nanocomposites were characterized with X-ray diffraction (XRD), Fourier transform infrared spectroscopy and transmission electron microscopy. The magnetic properties were investigated with a vibrating sample magnetometer. The peroxidase-like catalytic activity of the nanocomposites was investigated by colorimetric and electrochemical tests with 3,3',5,5'-tetramethylbenzidine (TMB) and $H_2O_2$ as the substrates. The results show that the synthesis of the nanocomposites was successfully performed. XRD analysis confirmed the crystalline structures of the $Ni_xZn_xFe_2O_4/MWCNT$ nanohybrids and MWCNTs. The main peaks of the $Ni_xZn_xFe_2O_4/MWCNT$s crystals were presented. The $Ni_{0.25}Zn_{0.25}Fe_2O_4/MWCNT$ and $Ni_{0.5}Zn_{0.5}Fe_2O_4/MWCNT$ nanocatalysts showed nearly similar physicochemical properties, but the $Ni_{0.5}Zn_{0.5}Fe_2O_4/MWCNT$ nanocatalyst was more appropriate than the $Ni_{0.25}Zn_{0.25}Fe_2O_4/MWCNT$ nanocatalyst in terms of the magnetic properties and catalytic activity. The optimum peroxidase-like activity of the nanocatalysts was obtained at pH 3.0. The $Ni_{0.5}Zn_{0.5}Fe_2O_4/MWCNT$ nanocatalyst exhibited a good peroxidase-like activity. These magnetic nanocatalysts can be suitable candidates for future enzyme-based applications such as the detection of glucose and $H_2O_2$.

• 한국자기학회지
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• 제16권1호
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• pp.40-44
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• 2006

졸-겔법을 이용하여 나노 입자 $Zn_{0.5}Ni_{0.5}Fe_2O_4$를 제조하여 x선 회절법(XRD) 및 주사전자현미경(SEM) 측정을 통하여 결정학적 특성 및 입자의 크기를 연구하였으며, 제조된 나노 입자의 초상자성 성질을 Mossbauer분광법, 진동시료 자화율 측정기(VSM)를 이용하여 연구하였다 XRD및 SEM의 측정으로부터 열처리 온도가 $300^{\circ}C$에서 순수한 cubic spinel구조를 가지며, 이 때 열 처리한 시료의 평균입자 크기는 7nm인 균일한 구형상 임을 알 수 있었다 Mossbauer분광실험으로 $300^{\circ}C$에서 열처리한 입자가 상온에서 초상자성의 특성을 가지고 있음을 알 수 있었으며, 4.2K에서의 초미세자기장은 $H_{hf}$ (B-자리)=510, $H_{hf}$(A-자리)=475 kOe, 이성질체 이동 값은 0.37(B-자리), 0.33mm/s(A-자리)로 분석되었다. VSM측정 결과로부터 상온에서 초상자성 특성을 갖는 7nm $Zn_{0.5}Ni_{0.5}Fe_2O_4$의 차단온도 $T_B$는 90 K로 결정하였으며, 자기이방성상수 $K=1.6\times10^6\;erg/cm^3$ 값을 얻었다.

• 한국재료학회지
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• 제9권12호
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• pp.1234-1239
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• 1999

$Ni_{0.5}-Zn_{0.4}-X_{0.1}{\cdot}Fe_2O_4$의 조성에서 X를 각각 Cu, Mg, Mn으로 치환시켜 치환원소에 따른 결정구조와 형상, 입도 및 자기적 성질을 비교 분석하여고, Network Analyzer을 이용하여 $Ni_{0.5}-Zn_{0.4}-X_{0.1}{\cdot}Fe_2O_4$-Rubber Composite의 재료정수 및 전파흡수특성에 대하여 비교 조사하였다. 치환원소에 관계없이 동일한 결정구조와 형상 및 입도를 나타냈고, VSM 분석결과 치환원소에 관계없이 동일한 자화값을 가지며, Mg로 치환된 경우 가장 큰 보자력과 자기이력손실을 나타냈다. 또한 Mn으로 치환된 경우 가장 높은 유전손실(${\varepsilon}_r"/{\varepsilon}_r'$)을, Cu로 치환된 경우에는 가장 큰 자기손실(${\mu}_r"/{\mu}_r'$)을 나타냈다. 4mm의 두께로 제조한 Compos-Composite에서는 Mg로 치환된 시료가 2GHz에서 -40dB이상의 가장 우수한 전파흡수특성을 나타내었다.

• 한국자기학회지
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• 제24권3호
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• pp.81-85
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• 2014

$BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ 나노복합체 페라이트는 솔-젤 연소법으로 합성하였고, 합성된 나노복합체 페라이트를 $600{\sim}900^{\circ}C$ 범위에서 1시간 동안 하소하였다. XRD 분석 결과, 경자성/연자성 나노복합체에서 경자성과 연자성이 공존하고 있음을 확인하였다. 나노복합체의 입자크기는 90 nm보다 작게 나타났다. 나노복합체는 단일 페라이트의 hysteresis 곡선과 같은 모양을 나타내었으며, 이로서 경자성과 연자성 사이에 exchange coupling이 잘 되었음을 확인할 수 있었다. 경자성/연자성 나노복합체 페라이트의 포화자화 값은 연자성보다 낮고 경자성보다 높았다. 잔류자화 값은 경자성과 연자성보다 크게 나타났고, 전체적으로 $(BH)_{max}$이 향상되었음을 확인할 수 있었다.

• 한국세라믹학회지
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• 제28권3호
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• pp.225-233
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• 1991

In this study, we tried to find out the appropriate synthetic condition and magnetic properties of Ni-Zn ferrite {(NixZn1-x)Fe2O4} powders (where X=0, 0.1, 0.2, 0.3, ……0.9, 1). Ferrite powders were prepared by wet-direct method at 86℃ for 6hrs from FeCl36H2O, NiCl26H2O, and ZnCl2. The powders of (NixZn1-x)Fe2O4 (where X=0.4, 0.5, 0.6) have a good crystallinity, but the other ferrite powders consist of crystal and precursor ferrite. The ferrite powder's lattice constant is increased when ratio of ZnO contant is increased in the ferrite composition. And initial permeability was measured after sintering, result indicated regular pattern except (Ni0.4Zn0.6)Fe2O4 when the frequency were changed 10KHz to 10MHz.

• 한국항해학회지
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• 제22권4호
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• pp.69-75
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• 1998

The super wideband electromagnetic wave absorber in RF-A-PF type has been proposed, which can be used for an anechoic chamber, wall material to prevent TV ghost, etc, In this paper, $Ni_x-Mg_{0.1}-Zn_(1-x-0.1){\cdot}Fe_2O_4$ Ferrite Powder has been fabricated. Using this, then, [$Ni_x-Mg_{0.1}-Zn_(1-x-0.1){\cdot}Fe_2O_4$-Rubber composite for RF-layer in the RF-A-PF type absorber has been fabricated and its characteristics has been analyzed. As a result, it has been shown that the $Ni_x-Mg_{0.1}-Zn_(1-x-0.1){\cdot}Fe_2O_4$-Rubber composit with the quantity $_x$ of $Ni_x$ between 0.5 and 0.6 is suitable for the RF-layer in the case of which the grain size is sub-micrometer order.

• 한국세라믹학회지
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• 제28권4호
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• pp.305-314
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• 1991

This study was conducted to research the formation and the color development of NiO-ZnO-Fe2O3-TiO2-SnO2 system for the purpose of synthesizing the spinel pigments which are stable at high temperature. After preparing ZnO-Fe2O3 as a basic composition, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.Fe2O3 system, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.TiO2 system, and {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.SnO2 system were prepared with {{{{ chi }}=0, 0.2, 0.5, 0.7, 1 mole ratio respectively. The manufacturing was carried out at 128$0^{\circ}C$ for 30 minutes. The reflectance measurement and the X-ray analysis of these specimens were carried out and the results were summarized as follows. 1. In the specimens which included NiO, it was difficult for the spinel structure to be formed. 2. As increasing the contents of NiO and Fe2O3, all the groups which were yellow or green colored changed to brown. 3. NiO-ZnO-Fe2O3 system and NiO-ZnO-TiO2 system formed the spinel structure and the illmenite structure appeared in NiO-TiO2 system.

• 한국전기전자재료학회논문지
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• 제15권5호
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• pp.406-411
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• 2002

Ni-Zn ferrite is required to have predominant and stable characteristics in the range of high frequency for the power line communication, so that microstructures and magnetic properties such as power loss and initial permeability in $Ni_{0.8}Zn_{0.2}Fe_2O_4$ were investigated in terms of variable $Bi_2O_3,CaO$ and $V_2O_5$ contents. $Bi_2O_3$ and $V_2O_5$ liquid phase created during sintering process promoted sintering and grain growth but much of the closed pore existed in the grains. The grain size of the specimens with $V_2O_5$ of over 0.5 wt% decreased as the result of "pinning effect"and the resonance frequency increased with CaO of 0.3we%. The high initial permeability of 81.52%, resonance frequency of 17.05 MHz and low power loss of 17,858 kW/$\textrm{m}^3$ were obtained from the samples with $Bi_2O_3$ of 0.5, CaO of 0.3, and $V_2O_5$ of 0.7 wt%.