• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.377-377
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• 2010

FINEMET type nanocrystalline materials synthesized by controlled crystallization of amorphous ribbons[1] exhibit excellent soft magnetic properties making them attractive for technological applications. Present work reports the electronic structure studies of Co-substituted FINEMET to get information on the effect of successive Co substitution on local environment around Fe and Co atom by using near edge x-ray absorption fine structure (NEXAFS) and x-ray magnetic circular dichroism (XMCD) measurements. NEXAFS spectroscopy and XMCD measurements have been carried out at Fe $L_{3,2}$ and Co $L_{3,2}$-edges to investigate the chemical states and electronic structure of FINEMET [$(Fe_{100-x}Co_x)_{78}Si_9Nb_3Cu_1Ba$](0$L_{3,2}$-edge reveal that Fe is in 2+ state and in tetrahedral symmetry with other elements. The magnetic properties exhibiting soft magnetic behavior[2] are discussed on the basis of the electronic structure studied through XMCD.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 1991년도 추계연구발표회 논문개요집
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• pp.60-61
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• 1991

• 한국자기학회:학술대회 개요집
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• 한국자기학회 1995년도 춘계연구발표회 논문개요집
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• pp.68-69
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• 1995

• Journal of Magnetics
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• 제1권1호
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• pp.31-36
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• 1996

An externally applied magnetic field during heat treating the $Nd_2Fe_{14}B/Fe_3B$ based spring magnet was found to enhance the exchange coupling between the hard and soft magnetic grains. More than 30% increase in $M_r/M_s$ values for melt-spun $Nd_2Fe_{73.5}Co_3$$(Hf_{1-x}Ga_x)B_{18.5}$ (x=0, 0.5, 1) alloys was resulted from a uniform distribution of $Fe_3B, \alpha-Fe$ and $Nd_2Fe_{14}B$ phases, and also from a reduced grain size of those phases by 20%. The externally applied magnetic field induced a uniform distribution of fine grains. A study of Mossbauer effect also report that the enhancement of total magnetization of nanocomposite $Nd_2Fe_{14}B/Fe_3B$ alloys is attributed to an increased formation of $Fe_3$B after magnetic annealing.

• 한국자기학회지
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• 제6권4호
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• pp.218-224
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• 1996

새로운 고성능 자심용 연자성 합금을 개발하기 위해, 급냉응고 방식에 의해 제조된 $Fe_{83-x}Al_{x}Nb_{5}B_{12}(X=1~5at%)$ 합금의 결정화거동 및 자기적 특성을 조사하였다. 3at% Al의 $Fe_{80}Al_{3}Nb_{5}B_{12}$ 합금이 조사된 Fe-Al-Nb-B계 합금중에서 가장 우수한 연자기 특성을 가지며, 이때 미세한 $\alpha-Fe$상 결정립 조직을 가지는 것으로 판명되었다. 또, 이 조성의 합금에 1 at%의 Cu를 첨가하면, 약 6~7 nm정도의 크기를 가지는 극히 미세한 결정립의 $\alpha-Fe$ 상조직이 얻어졌으며 이에 따라 대단히 현저한 연자기 특성의 향상이 실현되었다. 이때 초미세 결정구조 $Fe_{79}Al_{3}Nb_{5}B_{12}Cu_{1}$ 합금의 자기적 특성은 다음과 같다 : ${\mu}_{eff}(1\;kHz)=26,000,\;B_{10}=1.45\;T,\;H_{c}=25\;mOe,\;P_{c}(100\;kHz,\;0.2\;T)=55\;W/kg$.

• 한국자기학회지
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• 제16권5호
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• pp.249-254
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• 2006

CoFeNi 합금은 HDD, MEMS 분야에서 head core 재료로 쓰이는 permalloy(FeNi)합금보다 뛰어난 우수한 자기적 특성을 가진 재료로써 최근 많이 연구되어지고 있다. 전기도금된 CoFeNi합금 박막의 열처리에 따른 미세구조 변화와 결정학적 특성이 자기특성에 미치는 영향을 조사하였다. 삼원계 합금을 열처리하면 전기도금 시 결정의 크기와 결정구조의 변화가 자기특성에 영향을 미친다. 이를 조사하여 열처리를 통하여 얻어지는 CoFeNi계 박막의 자기 특성을 향상시키고자 하였고, $300{\sim}400^{\circ}C$까지 열처리를 함으로써 보자력을 최소화하고 포화자화 값을 증가시켰다. 포화자화 값의 증가는 bcc상의 생성으로 야기되는 것으로 판단된다.

• 한국자기학회지
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• 제13권4호
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• pp.133-154
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• 2003

A comprehensive review is given in this article on magnetic and magnetostrictive properties of nanogranular Co-Fe based alloys, with a particular emphasis on high frequency applications. Structural and physical properties are firstly described, followed by magnetic and magnetostrictive properties. Materials of both thin film and bulk forms are considered. A detailed description on high frequency characteristics of Co-Fe based soft magnetic thin films is then presented.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1989년도 춘계학술대회 논문집
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• pp.49-51
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• 1989

The effect of Mo elenent and annealing condition on the magnetic properties were investigated in Fe$_{80}$B$_{12}$Si$_{8}$ amorphous alloy. With increasing Mo contents, soft magnetic properties were improved by decreasing coercive force and increasing maximum permeability. These improvements were attributed to the decreasing of magnetostriction by Mo addition. The annealing treatment also improved the soft magnetic properties of (Fe$_{1-x}$ Mo$_{x}$)$_{80}$ B$_{12}$ Si$_{8}$ amorphous alloys. It could be thought that these improvements were ascribed to the relaxation of internal stress.nal stress.ess.

• 한국표면공학회지
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• 제36권6호
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• pp.455-460
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• 2003

Microstructural and magnetic properties of nanocrystalline Fe-46 wt%Ni and Fe-36 wt%Ni alloys were investigated. Alloys were prepared by the electrodeposition process. The electrolytes were iron sulfate/nickel chloride-based and iron chloride/nickel sulfamate-based solutions. Fe-46 wt%Ni alloy was FCC structure with grain size of 10 nm, but FCC and BCC phases were found in Fe-36 wt%Ni alloy and its grain size was smaller. Effective permeability of Fe-36 wt%Ni alloy was higher than that of Fe-46 wt%Ni alloy in the high frequency range because of large electrical resistivity and small eddy current loss resulted from grain size decrease. Up to $300^{\circ}C$ of annealing temperature, grain growth of Fe-Ni alloys slowly occured. Conversely, annealing above $450^{\circ}C$ led to a drastic grain growth. In that case, effective permeability was decreased at the temperature lower than $300^{\circ}C$ but at $300^{\circ}C$ or higher effective permeability was increased. At the high frequency of 1 MHz, electrodeposited Fe-Ni alloys had higher effective permeability with an decrease in the grain size.

• 한국자기학회지
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• 제16권4호
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• pp.197-200
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• 2006

RF magnetron reactive sputtering법으로 CoFeHfO 박막을 상온에서 제작하여 산소분압에 따른 포화자화, 보자력, 이방성자계를 조사하였다. 최적조건인 산소분압 8%에서 제조한 $Co_{39}Fe_{34}Hf_{9.5}O_{17.5}$ 박막은 포자자속밀도($4{\pi}M_s$) 19kG, 보자력($H_c$) 0.37Oe, 이방성자계($H_k$) 48.62Oe의 우수한 연자성을 나타내었다. CoFeHfO 박막의 전기비저항은 산소분압이 늘어남에 따라 증가하는 경향을 나타내었으며 우수한 연자기적 성질을 가지는 $Co_{39}Fe_{34}Hf_{9.5}O_{17.5}$ 박막의 경우, 300 ${\mu}{\Omega}cm$의 높은 전기비저항과 48.62 Oe의 높은 이방성자계 때문에 $Co_{39}Fe_{34}Hf_{9.5}O_{17.5}$박막이 고주파에서 우수한 연자기 특성을 가지는 것으로 사료된다.