• 한국재료학회지
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• 제12권11호
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• pp.880-882
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• 2002

We have prepared magnetic thin films of FeSiB by sputtering and examined microstructure and magnetic properties of the annealed films in order to investigate the feasibility of the films to microsensor application. Effects of vacuum annealing on the magnetic properties of $Fe_{84}$$Si_{6}$$B_{10}$ films have been examined as a function of temperature. The heating rate and the holding time were 10 K/min and 1 hour, respectively. Vacuum condition was held during cooling to prevent oxidation of the films. The coercivity did not show any noticeable change (~1500 A/m), although the grain size of the crystalline phase in the annealed films increased gradually up to about 16 nm until 673 K. However, both the grain size and the coercivity increased steeply when the annealing temperature increased over 723 K. Since the saturation magnetization is closely related to the phase evolution, the variation of the saturation magnetization of the annealed films was similar to that of the ribbon materials; the thin films were transformed from amorphous to crystalline with $\alpha$-(Fe,Si) phase by increasing annealing temperature.

• 한국자기학회지
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• 제8권3호
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• pp.138-143
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• 1998

본 연구에서는 RF magnetron reactive sputtering system에 의해 증착된 FeBN막의 자기박막의 자기특성과 비저항의 변화를 연구하엿다. 막의 자기특성과 비저항의 변화는 막내에 첨가되는 B, Si, N의 조성에 따라 큰 변화를 나타내었으며, 소량의 N의 첨가에 따라 우수한 자기 특성과 비저항이 증가하였다. 그러나 과도한 N의 첨가는 Fe4N과 같은 질화물의 형성으로 비저항은 증가하였으나 자기 특성은 열화되었다. 제조된 FeBN과 FeSiN 자성막은 1 Oe이하의 보자력과 18~19kG의 포화자속말도, 그리고 1000이상의 투자율을 갖는 우수한 연자기 특성을 보였다. 이때의 막의 조성은 AES(Auger Electron Spectroscpy)로 분석하여 Fe75(BN)25, Fe78(BN)25이었으며 비저항값은 100~120$\mu$$\Omega$-cm이었다.

• 한국전기전자재료학회논문지
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• 제16권12S호
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• pp.1305-1309
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• 2003

To utilize FeCoSiB amorphous films for magnetoelastic sensors, the temperature dependency of magnetization (M-T curve) and the magnetization properties of the amorphous films were investigated in this study. As the amount of cobalt In the films increased, the Curie temperature decreased but the crystallization temperature increased. In addition to this, the crystallization temperature was lower than the Curie temperature in the film containing 20 at% cobalt. The optimized annealing condition was set up by analyzing the H-T curve. And then, the amorphous film that has excellent magnetic properties and uni-axal anisotropy could be prepared for construction of the magnetoelastic sensor devices. The coercive force of the film was below 0.5 Oe and the anisotripic field was about 5 Oe.

• Journal of Magnetics
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• 제10권4호
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• pp.145-148
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• 2005

Effect of vacuum annealing on the microstructures and magnetic properties of $Fe_{84}Si_6B_{10}$ films has been investigated as a function of annealing temperature. X-ray diffraction and transmission electron microscopy were employed to analyze crystallization behavior of the films. Permeability of the films was measured at various frequencies by one-turn coil method. When the films were annealed below 673 K, the coercivity of the films did not change a lot (${\~}$1500 A/m) although the grain size of a crystalline phase in the partially crystallized films increased gradually up to about 16 nm. It then increased rapidly as the films became almost fully crystalline mostly with $\alpha$-(Fe,Si) phase at and above 723 K. On the other hand, the electrical resistivity of the films decreased monotonically with the increase of annealing temperature. The permeabilities of the films annealed at 473${\~}$673 K were all over 1000, showing the optimum value of 3500 at 523 K, and almost constant up to 300 MHz. However, those of the as-deposited and fully crystallized films were lower than 1000 and unstable at the same frequency range.

• 한국진공학회지
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• 제9권4호
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• pp.389-393
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• 2000

Metalloid의 양이 거의 일정(B, Si 각각 l0 at.% 정도)하게 유지되는 상황에서 FeCoSiB 박막내의 Co함량 증가가 여러 가지 자기적 특성에 미치는 효과, 그리고 열처리 온도와 시간에 따른 막의 자성특성 변화를 관찰해 보았다. dc magnetron sputter를 이용하여 비정질 합금 자성박막을 증착하였으며, 비정질의 막을 형성하기 위하여 기판은 수냉하였다. 막의 조성은 순철 target위에 올려놓는 pellet의 수를 조절하여, 대략 $Fe_{80-X}Co_XBi_{10}Si_{10}$ (X=8~18 at.%)로 하였으며, 증착된 막의 조성은 ICP 분석법을 이용하여 조사하였다. Sputtering에 의해 증착된 박막의 결정화 유무는 XRD로 분석하였으며, 보자력과 포화 자화값 등의 자기적 성질은 VSM을 이용하여 측정하였다. 실험결과에 따르면 막내 Co 함량이 증가함에 따라 보자력은 감소하는 경향을 나타내었으며, 포화자화 값은 Co 함량이 대략 10 at.%에 도달할 때까지는 증가하다가 그 이상에서는 감소하는 현상을 나타내었다. 그리고 증착 과정중에 막에 생기는 잔류응력의 제거효과를 관찰하기 위해 열처리 온도(100, 200, $300^{\circ}C$)와 시간(0~60분)을 변화시키며 실험한 결과, 예상되었던 바대로 잔류응력의 감소로 인해 Co 첨가시와 마찬가지로 보자력이 감소하는 결과를 나타내었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1996년도 재료학회 추계학술발표회
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• pp.17-17
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• 1996

• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 추계학술발표강연 및 논문개요집
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• pp.138-138
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• 1998

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.786-787
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• 2006

The magnetic inductance of nanocrystalline $Fe_{73}Si_{16}B_7Nb_3Cu_1$ and an amorphous FeSiB powder sheet has been investigated to identify RFID performance. The powder was mixed with binder and solvent and tape-casted to form films. Results show annealing significantly influenced on the inductance of the material. The surface oxidation of the particles was the main reason for the reduced inductance. The maximum inductance of $Fe_{73}Si_{16}B_7Nb_3Cu_1$ alloy was about $88{\mu}H$ at 17.4 MHz, about 65% greater compared to the FeSiB alloy. The higher inductance in the nanocrystalline alloy indicates it may be used as a potential replacement of current RFID materials.

• 한국분말재료학회지
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• 제25권5호
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• pp.375-378
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• 2018

Conductive and dielectric SiC are fabricated using electroless plating of Ni-Fe films on SiC chopped fibers to obtain lightweight and high-strength microwave absorbers. The electroless plating of Ni-Fe films is achieved using a two-step process of surface sensitizing and metal plating. The complex permeability and permittivity are measured for the composite specimens with the metalized SiC chopped fibers dispersed in a silicone rubber matrix. The original non-coated SiC fibers exhibit considerable dielectric losses. The complex permeability spectrum does not change significantly with the Ni-Fe coating. Moreover, dielectric constant is sensitively increased with Ni-Fe coating, owing to the increase of the space charge polarization. The improvements in absorption capability (lower reflection loss and small matching thickness) are evident with Ni-Fe coating on SiC fibers. For the composite SiC fibers coated with Ni-Fe thin films, a -35 dB reflection loss is predicted at 7.6 GHz with a matching thickness of 4 mm.

• 한국자기학회지
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• 제10권6호
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• pp.280-294
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• 2000

RF-DC 마그네트론 스퍼터링을 이용하여 5$\times$$10^{-3}$ Torr의 알곤 가스 분위기에서 [(300nm)Ta/(500nm)NdFeB/(300nm)Ta] 영구자석 박막을 제조한 후 이의 미세구조 및 자기특성을 조사하였다 650-75$0^{\circ}C$로 가열된 Si 기판위에 성막한 [Ta/ NdFeB/Ta] 박막은 수직자기이방성과 함께 우수한 경자기특성을 나타내었으며, 특히 기판온도 $650^{\circ}C$와 $700^{\circ}C$에서 제조된 박막은 막면에 수직한 방향으로 각각 20 MGOe의 최대자기에너지적과 18.9 kOe의 큰 고유보자력을 나타내었다.