• 제목/요약/키워드: zinc ferrite

검색결과 43건 처리시간 0.023초

전기방사법에 의한 NiZn 페라이트 나노섬유의 제조 및 특성 연구 (Preparation and Characterization of NiZn-Ferrite Nanofibers Fabricated by Electrospinning Process)

  • 주용휘;남중희;조정호;전명표;김병익;고태경
    • 한국세라믹학회지
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    • 제46권1호
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    • pp.74-80
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    • 2009
  • Electrospinning process is the useful and unique method to produce nanofibers from metal precursor and polymer solution by controlled viscosity. In this study, the NiZn ferrite nanofibers were prepared by electrospinning with a aqueous metal salts/polymer solution that contained polyvinyl pyrrolidone and Fe (III) chloride, Ni (II) acetate tetrahydrate and zinc acetate dihydrate in N,N-dimethylformamide. The applied electric field and spurting rate for spinning conditions were 10 kV, 2 ml/h, respectively. The obtained fibers were treated at $250^{\circ}C$ for 1 h to remove the polymer. Finally, the NiZn ferrite fibers were calcined at $600^{\circ}C$ for 3 h and annealed at $900{\sim}1200^{\circ}C$ in air. By tuning the viscosity of batch solution before electrospinning, we were able to control the microstructure of NiZn ferrite fiber in the range of $150{\sim}500\;nm$ at 770 cP. The primary particle size in $600^{\circ}C$ calcined ferrite fiber was about 10 nm. The properties of those NiZn ferrite fibers were determined from X-ray diffraction analysis, electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, thermal analysis, and magnetic measurement.

Crystallographic and Magnetic Properties of Co, Zn, Ni-Zn Substituted Nano-size Manganese Ferrites Synthesized by Sol-gel Method

  • Noh, Kwang Mo;Lee, Young Bae;Kwon, Woo Hyun;Kang, Jeoung Yun;Choi, Won-Ok;Chae, Kwang Pyo
    • Journal of Magnetics
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    • 제21권3호
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    • pp.308-314
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    • 2016
  • Cobalt-, zinc-, and nickel-zinc-substituted nano-size manganese ferrite powders, $MnFe_2O_4$, $Mn_{0.8}Co_{0.2}Fe_2O_4$, $Mn_{0.8}Zn_{0.2}Fe_2O_4$ and $Mn_{0.8}Ni_{0.1}Zn_{0.1}Fe_2O_4$, were fabricated using a sol-gel method, and their crystallographic and magnetic properties were subsequently studied. The $MnFe_2O_4$ ferrite powder annealed at temperatures above 523 K exhibited a spinel structure, and the particle size increased as the annealing temperature increased. All ferrites annealed at 773 K showed a single spinel structure, and the lattice constants and particle size decreased with the substitution of Co, Zn, and Ni-Zn. The $M{\ddot{o}}ssbauer$ spectrum of the $MnFe_2O_4$ ferrite powder annealed at 523 K only showed a doublet due to its superparamagnetic phase, and the $M{\ddot{o}}ssbauer$ spectra of the $MnFe_2O_4$, $Mn_{0.8}Co_{0.2}Fe_2O_4$, and $Mn_{0.8}Zn_{0.2}Fe_2O_4$ ferrite powders annealed at 773 K could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. However, the $M{\ddot{o}}ssbauer$ spectrum of the $Mn_{0.8}Ni_{0.1}Zn_{0.1}Fe_2O_4$ ferrite powder annealed at 773 K consisted of two Zeeman sextets and one quadrupole doublet due to its ferrimagnetic and paramagnetic behavior. The area ratio of the $M{\ddot{o}}ssbauer$ spectra could be used to determine the cation distribution equation, and we also explained the variation in the $M{\ddot{o}}ssbauer$ parameters by using this cation distribution equation, the superexchange interaction and the particle size. Relative to pure $MnFe_2O_4$, the saturation magnetizations and coercivities were larger in $Mn_{0.8}Co_{0.2}Fe_2O_4$ and smaller in $Mn_{0.8}Zn_{0.2}Fe_2O_4$, and $Mn_{0.8}Ni_{0.1}Zn_{0.1}Fe_2O_4$. These variations could be explained using the site distribution equations, particle sizes and magnetic moments of the substituted ions.

Preparation of superparamagnetic ZnFe2O4 submicrospheres via a solvothermal method

  • Ma, Jie;Chen, Bingjie;Chen, Bingkun;Zhang, Shuping
    • Advances in nano research
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    • 제5권2호
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    • pp.171-178
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    • 2017
  • Superparamagnetic Zinc ferrite submicropheres are firstly synthesized via a one-pot solvothermal approach at $200-215^{\circ}C$ for 4-8 hours. $ZnCl_2$, $FeCl_3$ and NaAc are used as precursors with ethylene glycol solvent. The X-ray diffraction (XRD) data indicate that $ZnFe_2O_4$ nanoparticles with the grain size around $15{\pm}3nm$ can be successfully synthesized via the one-pot method. The scanning/transmission electronic microscope (SEM/TEM) images further show the samples are submicrospheres self-assembled by nanoparticles with size about 375-500 nm changed with reaction conditions. Room-temperature vibration magnetic strength measurements (VMS) demonstrates the as-obtained $ZnFe_2O_4$ submicrospheres show prefect superparamagnetism, whose coercivity force and remanence are practically nil. The reaction temperature and time influence on the crystallinity, diameter, saturated magnetic intensity and morphology of the particles.

산화철을 이용한$H_2S$ 제거 ($H_2S$ Desulfurization Using Iron Oxide Sorbent)

  • B.K. Kho;Lee, W.R.;Kim, H.J.;Lee, W.M.
    • 한국에너지공학회:학술대회논문집
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    • 한국에너지공학회 2000년도 추계 학술발표회 논문집
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    • pp.73-77
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    • 2000
  • A great deal of research has been carried out in the last twenty some years to develop high temperature desulfurization. For example, the efficiency of advanced power generation processes based on the integrated gasification combined cycle (IGCC) can be increased significantly with high temperature desulfurization. Much of the recent high temperature desulfurization research has concentrated on zinc-based sorbents such as zinc ferrite(ZnFe$_2$O$_4$) and zinc titanate(ZnO.xTiO$_2$) due to its thermodynamic advantage in capturing H$_2$S molecules.(omitted)

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산화철 폐촉매로부터 합성된 NiZn- 페라이트의 자기적 특성 (Magnetic Properties of NiZn-ferrite Synthesized from Waste Iron Oxide Catalyst)

  • 황연;권순길;이효숙;제해준;박상일
    • 한국세라믹학회지
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    • 제38권12호
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    • pp.1162-1166
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    • 2001
  • 석유화학 공정 중 Styrene(SM) 공정에서 발생되는 산화철 폐촉매는 산업 폐기물로서 전량 매립되고 있는데, 이를 출발 원료로 사용하여 NiZn-페라이트를 합성하였고 그 자기적 특성을 조사하였다. 산화철 폐축매 펠렛을 분쇄한 후 NiO 및 ZnO를 혼합하여 90$0^{\circ}C$에서 하소하고 123$0^{\circ}C$에서 5시간 소결하여 스핀넬형 페라이트 소결체를 얻었다. N $i_{x}$ Z $n_{1-x}$F $e_2$ $O_4$(x=0.36, 0.50, 0.66)조성에 대하여 초투자율을 측정하였고, S-parameter를 측정하여 반사 감쇄량을 계산하였다. 산화철 폐촉매를 이용하여 X-band 주파수 영역에서 높은 전자파 흡수능을 갖는 전파흡수체를 제조할 수 있음을 확인하였다.다.

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Mössbauer Spectroscopic Studies of NiZn Ferrite Prepared by the Sol-Gel Method

  • Niyaifar, Mohammad;Mohammadpour, Hory;Rodriguez, Anselmo F.R.
    • Journal of Magnetics
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    • 제20권3호
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    • pp.246-251
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    • 2015
  • This study was aimed to study the effect of Zn content on the hyperfine parameters and the structural variation of $Ni_{1-x}Zn_xFe_2O_4$ for x = 0, 0.2, 0.4, 0.6, and 0.8. To achieve this, a sol-gel route was used for the preparation of samples and the obtained ferrites were investigated by X-ray diffraction, scanning electron microscopy, and $M{\ddot{o}}ssbauer$ spectroscopy. The formation of spinel phase without any impurity peak was identified by X-ray diffraction of all the samples. Moreover, the estimated crystallite size by X-ray line broadening indicates a decrease with increasing Zn content. This result was in agreement with the scanning electron microscopy result, indicating the reduction in grain growth with further zinc substitution. The room-temperature $M{\ddot{o}}ssbauer$ spectra show that the hyperfine fields at both the A and B sites decreased with increasing Zn content; however, the rate of reduction is not the same for different sites. Moreover, the best fit parameter showed that the quadrupole splitting values of B site increased from the pure nickel ferrite to the sample with x = 0.8.

Effect of Aggregates on the Microstructure in Manganese Zinc Ferrite

  • Shin, Hyo-Soon;Lee, Dae-Hee;Kim, Chang-Bum;Kim, Nam-Kyung;Lee, Suk-Kee;Lee, Byung-Kyo
    • 한국세라믹학회지
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    • 제40권1호
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    • pp.1-4
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    • 2003
  • To study the effect of aggregates on the microstructure of sintered bodies, Mn-Zn ferrite powders were prepared by an alcoholic dehydration method. Aggregate powders and reground powders were used as seeds and matrices, respectively. The mixing ratios for the aggregate and reground powders were varied with the sintering temperatures. Green densities were measured with changes in forming pressure and they were related to the microstructures of the sintered bodies. The aggregates proved to be capable of acting as seeds for abnormal grain growth. When the green density difference between the aggregate and the matrix was large, the aggregate could become the seed of abnormal grain growth. As the forming pressure increased, the more aggregates became seeds of abnormal grain growth.

$SiO_2$와 CaO 첨가가 Mn-Zn Ferrites의 전자기적 물성에 미치는 영향 (Effect of CaO and $SiO_2$ Addition on the Electromagnetic Properties of Mn-Zn Ferrites)

  • 서정주;신명승;한영호
    • 한국세라믹학회지
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    • 제32권9호
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    • pp.1033-1039
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    • 1995
  • The current experiment has quantitatively investigated the effect of the content of CaO and SiO2 on the microstructure, density, electrical resistivity, power loss and initial permeability of manganese zinc ferrites. The density increased initially with CaO and SiO2 content and the further addition showed an adverse effect. The excess addition of CaO and SiO2 developed a discontinuous grain growth with numerous pores inside grains and lowered the electrical resistivity. The initial permeability decreased with increasing the content of SiO2. The samples with relatively low power loss showed that half of the total loss at 10$0^{\circ}C$, 100 kHz and 2000 Gauss was due to the eddy current loss.

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고온정제를 적용한 IGCC 플랜트 성능 해석에 관한 연구(I) (Plant Performance Analysis for IGCC Employing HGCU(I))

  • 이윤경;서석빈;김종진
    • 에너지공학
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    • 제9권3호
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    • pp.157-162
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    • 2000
  • 기존의 IGCC의 장점인 고효율 플랜트의 특성을 살리기 위해 고온정제를 적용하는 경우 조건변화에 따른 플랜트 성능의 영향을 관찰하고자 본 연구를 수행하였다. IGCC에 고온정제 공정을 적용하여 구성한 모델은 연구 목적에 알맞은 범위의 건전성을 가진 것으로 나타났으며 기타 조건을 동일하게 설정한 경우 저온 정제 공정(MDEA amine) 적용에 비해 플랜트 효율이 약 2.7% 가량 상승하였다. 한편 동일한 고온정제 공정이라도 적용하는 흡수제를 zinc titanate에서 zinc ferrite로 달리 하는 경우 탈황제의 화학 반응상 특성 및 차이점으로 인해 연료가스의 발열량 변화를 유발하므로 결과적으로 약 0.5%의 플랜트 효율 손실이 발생함을 알 수 있었다. 또한 탈황 온도 350~$650^{\circ}C$ 사이의 온도범위에 대해 민감도 분석을 실행하였으며 민감도 분석 결과 전제 온도의 증가와 플랜트 효율은 정비례하지 않으며 50$0^{\circ}C$ 이상의 정제 온도를 적용한 경우는 거의 비슷한 효율을 나타내었다. 이와 같은 결과는 정제 온도를 증가시킴으로 인해 가스터빈에 공급되는 연료가스의 온도는 높아지지만 적용한 가스터빈의 출력 및 연소 온도가 제한되어 있어 고온정제를 적용함으로써 얻어지는 이득을 가스터빈에서 충분히 보상하지 못하고 한편으로 고온정제를 채택함으로써 저온정제 적용시 보다 syngas cooler에서 회수할 수 있는 헌열이 줄어듦으로 인한 증기 터빈 출력의 감소가 커지기 때문으로 분석되었다.

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