• 한국자기학회:학술대회 개요집
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• 한국자기학회 1993년도 춘계연구발표회 논문개요집
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• pp.86-87
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• 1993

• 한국세라믹학회지
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• 제31권3호
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• pp.235-240
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• 1994

The electric and magnetic properties of Mg1.9-2xMn0.05Fe4xO4+${\gamma}$+2wt% Al2O3, and its microstructure have been investigated as a function of ferrite composition (x=0.45, 0.5, 0.55). The microstructure turned out to be independent on the ferrite composition. The resistivity was decreased with increasing Fe contents, whereas the Curie temperature decreased. Saturation magnetization was varied from 1741 to 2022 G with composition, and squareness ratio (SR), coercive force (BHc) were decreased and increased with increasing Fe contents respectively, so the sample which SR and BHc were 0.97 Oe and 1.49 Oe can be attainable at x=0.45.

• 대한금속재료학회지
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• 제49권3호
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• pp.256-263
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• 2011

We have synthesized Al-Co/AlN-Co multilayer films with different layer thicknesses by using a Two-Facing Target Type dc Sputtering (TFTS) system. The deposited films were annealed isothermally at different temperatures and their microstructure, magnetic properties and resistivity were investigated. The magnetization of the as-deposited films was found to be very small, irrespective of layer thickness. It was found that the annealing conditions and layer thickness ratio of Al-Co to AlN-Co (LTR) were able to control the microstructure, as well as the physical properties of the prepared films. The resistivity and magnetization increased and the coercivity decreased with a decreasing LTR. A high resistivity of 2500 ${\mu}{\Omega}-cm$, a magnetization of 360 $emu/cm^3$, and a coercivity of 5 Oe were obtained for the films with LTR=0.175.

• 한국분말재료학회지
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• 제13권5호
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• pp.336-339
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• 2006

Magnetic properties of nanostructured materials are affected in complicated manner by their microstructure such as pain size (or particle size), internal strain and crystal structure. Thus, studies on the synthesis of nanostructured materials with controlled microstructure are necessary fur a significant improvement in magnetic properties. In the present work, nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated from the powder mixtures of (99.9% purity) $FeCl_2$ and $CoCl_2$ by chemical solution mixing and hydrogen reduction.

• 한국분말재료학회지
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• 제11권1호
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• pp.16-21
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• 2004

The nano-sized Co particles were successfully synthesized by chemical vapor condensation (CVC) process using the precursor of cobalt carbonyl ($Co_2(CO)_8$). The influence of carrier gases on the microstructure and magnetic properties of nanoparticles was investigated by means of XRD, TEM, XPS and VSM. The Co nano-particles with different phases and shapes were synthesized with a change of carrier gas : long string morphologies with coexistence of fcc and hcp structure in Ar carrier gas condition; finer Co core in a mass of cobalt oxide with only fcc structure in He; rod type cobalt oxide phase in Ar＋6vol％$O_2$. The saturation magnetization and coercivity was lower in Co nanoparticles synthesized in He carrier gas, due to their finer size.

• 한국세라믹학회지
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• 제30권12호
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• pp.1015-1022
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• 1993

The formation process of polycrystalline YIG(Y3Fe5O12) prepared by conventional method in Fe2O3-Y2O3 system was investigated. Effect of the microstructure of sintered body on electromagnetic properties was also investigated. Orthoferrite (YFeO3) was formed between 900 and 110$0^{\circ}C$. Formation of YIG phase begin at 110$0^{\circ}C$ with sharp increased saturation magnetization simultaneously. YIG phase is identified as single phase above 120$0^{\circ}C$. The microstructures and electromagnetic properties of sintered bodies are varied due to calcination condition of starting materials. The sintered YIG of calcined sample at 110$0^{\circ}C$ has such magnetic properties as Bs=1580G, BHC=1.89Oe, Tc=570K, ΔH(9.3GHz)=78Oe.

• 전기화학회지
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• 제6권3호
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• pp.208-211
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• 2003

본 연구에서는 CoP나노선재의 미세구조 및 크기에 따른 자기적 성질의 변화를 고찰하였다. 우선 나노선재를 제조하기 위하여 기공의 직경이 각각 20nm, 200nm인 알루미나 형틀을 제조하였고, 이 형틀을 이용하여 전기도금 방법으로 CoP나노선재를 제조하였다. 직경이 20nm인 나노선재의 경우 나노선재의 길이방향으로의 각형성 및 보자력이 각각 0.8, 2600 Oe으로서 지금까지 보고된 나노선재들에 비해 우수한 자기적 성질을 나타내었고 전기도금 시 전류밀도의 영향이 거의 없었다. 그러나 직경이 200nm인 나노선재는 나노선재의 길이방향으로 각형성 및 보자력이 각각 0.15, 1200 Oe으로 20nm나노선재보다 현격하게 감소하였으며 나노선재의 자기적 성질이 전류밀도에 따라 많은 영향을 받고 있음을 확인하였다 즉, 상대적으로 낮은 전류밀도에서 제조된 나노선재일 수록 나노선재와 평행한 방향으로 자화용이축이 배향되어 길이방향으로 각형성 및 보자력이 증가하였다.

• 한국자기학회지
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• 제5권5호
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• pp.519-523
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• 1995

The Fe-TM-C-N nanocrystalline films (TM : Hf, Zr and Nb) are investigated to examine the relation between microstructure and soft magnetic properties. In these films, as the atomic radius of TM element increases, $P_{N2}$ which was added to get good soft magnetic properties was decreased and the maximum value of the permeability shifted to the high Fe range in the composition diagram. The best soft magnetic properties achieved in these films are : Hc of 0.15 Oe, $\mu_{eff}$ of 7800 (1MHz) and $4{\pi}M_{s}$ of 17.5 kG in Fe-Hf-C-N film ; Hc of 0.06 Oe, $\mu_{eff}$ of 2750 (1MHz) and $4{\pi}M_{s}$ of 16.8 kG in Fe-Zr-C-N film and Hc of 0.31 Oe; $\mu_{eff}$ of 2100 (1MHz) and $4{\pi}M_{s}$ of 15.5 kG in Fe-Nb-C-N film. It was considered that the stronger the bonding force between TM and C(N), the finer TM(C,N) phase is precipitated and therefore, the finer $\alpha$-Fe grains are formed. The effective permeability of the Fe-Zr-C-N films and Fe-Nb-C-N films remains nearly constant up to 10 MHz.

• 대한금속재료학회지
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• 제50권3호
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• pp.248-255
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• 2012

AlN thin films containing various amounts of Co, AlN-Co, and Al-Co alloy particles were prepared using a two-facing-target type dc reactive sputtering (TFTS) system. The as-deposited films exhibited the variable nature expected from an AlN-rich phase, and an amorphous-like phase, depending on the Co content in the films. Specific favorable microstructures were prepared by optimizing annealing conditions. Those microstructures and their magnetic properties and resistivity were investigated. As-deposited films showed very small saturation magnetization and an amorphous-like structure. However, when annealed, the as-deposited amorphous-like phase decomposes into phases of AlN, Co and Al-Co. These annealing induced changes in the microstructure improve the magnetization and resistivity of the films. Further improvement of soft magnetic properties could lead to the material being used for high density magnetic recording head material.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.120-121
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• 2006

Magnetic properties of nanostructured materials are affected by the microstructures such as grain size (or particle size), internal strain and crystal structure. Thus, it is necessary to study the synthesis of nanostructured materials to make significant improvements in their magnetic properties. In this study, nanostructured Fe-20at.%Co and Fe-50at.%Co alloy powders were prepared by hydrogen reduction from the two oxide powder mixtures, $Fe_2O_3$ and $Co_3O_4$. Furthermore, the effect of microstructure on the magnetic properties of hydrogen reduced Fe-Co alloy powders was examined using XRD, SEM, TEM, and VSM.