• Title/Summary/Keyword: amorphous magnetic material

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The Effects of Surface Insulation Layer on the Magnetic Properties of Nanocrystalline Alloy Ribbons (표면 절연층이 나노결정립 합금 리본의 자기적 특성에 미치는 영향)

  • Oh, Young-Woo
    • Journal of the Korean Magnetics Society
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    • v.17 no.6
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    • pp.226-231
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    • 2007
  • High frequency loss property of nanocrystalline amorphous ribbon with a high resistivity insulation layer of $TiO_2$ and $SiO_2$ was studied. The insulation layer was fabricated by sol-gel method using dip-coating. The optimum composition ratio of metal alkoxide and slurry for fabrication of insulation layer was established and insulation layer with high adhesion was coated on the nanocrystalline amorphous ribbon. Frequency loss of magnetic core material manufactured on nanocrystalline amorphous ribbon with the surface insulation layer decreased over 40 % compared with that of magnetic core material without surface insulation layer. The insertion loss of an inductive coupler, which was prepared by using magnetic core material coated insulation layer, decreased due to reduction of frequency loss for magnetic core material and insertion loss decreased in proportion to frequency.

Effect of Co-Substitution on the Crystallization and Magnetic Properties of a Mechanically Milled Nd15(Fe1-xCox)77B8 (x=0-0.6) Alloy

  • Kwon, H.W.;Yang, C.J.
    • Journal of Magnetics
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    • v.7 no.4
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    • pp.143-146
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    • 2002
  • Mechanical milling technique is considered to be a useful way of processing the fine Nd-Fe-B-type powder with high coercivity. In the present study, phase evolution of the $Nd_{15}(Fe_{1-x}Co_{x})_{77}B_{8}$ (x=0-0.6) alloys during the high energy mechanical milling and annealing was investigated. The effect of Co-substitution on the crystallization of the mechanically milled $Nd_{15}(Fe_{1-x}Co_{x})_{77}B_{8}$ amorphous material was examined. The Nd-Fe-B-type alloys can be amorphized completely by a high-energy mechanical milling. On annealing of the amorphous material, fine $\alpha$-Fe crystallites form first from the amorphous. These fine $\alpha$-Fe crystallites reacts with the remaining amorphous afterwards, leading to crystallization to $Nd_2Fe_{14}$B phase. The Co-substitution for Fe in $Nd_{15}(Fe_{1-x}Co_{x})_{77}B_{8}$ ($\mu$x=0∼0.6) alloys lower significantly the crystallization temperature of the amorphous phase to the $Nd_2Fe_{14}$B phase. The mechanically milled and annealed $Nd_{15}Fe_{77}B_8$ alloy without Co-substitution exhibits consistently better magnetic properties with respect to the alloys with Co-substitution.

Magnetic Properties of Co-Cr(-Ta)/Si Bilayered Thin Film (Co-Cr(-Ta)/Si 이층막의 자기적 특성)

  • 김용진;박원효;금민종;최형욱;김경환;손인환
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.3
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    • pp.281-286
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    • 2002
  • In odder to investigate the magnetic properties of CoCr-based bilayered thin films on kind of underlayer, we introduced amorphous Si layer to Co-Cr(-Ta) magnetic layer as underlayer. First, we prepared CoCr and CoCrTa single layer using the Facing Targets Sputtering system to investigate theirs properties. It was revealed that with increasing the film thickness of CoCr, CoCrTa single layer, crystalline orientation and perpendicular coercivity was improved. The CoCrTa thin film showed bettor crystalline and magnetic characteristics than CoCr thin film. As a result of investigating magnetic properties of CoCr and CoCrTa magnetic layer on introducing the Si underlayer, perpendicular coercivity and saturation magnetization of CoCr/Si and CoCrTa/Si bilayered thin film were decreased due to the increased grain size and diffusion of Si atoms to magnetic layer. And they showed constant with increasing the film thickness of Si thin film. However, in case of CoCrTa/Si bilayered thin film, in-plane coercivity was controlled low at about 250Oe. The c-axis orientations of CoCr/si and CoCrTa/Si bilayered thin film showed a good crystalline characteristics as about $2^{\circ}$.

A MICRO FLUXGATE SENSOR IN PRINTED CIRCUIT BOARD (PCB) (인쇄회로 기판에 내장된 마이크로 플럭스게이트 센서)

  • 최원열;황준식;나경원;강명삼;최상언
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07a
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    • pp.151-155
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    • 2002
  • This paper presents a micro fluxgate magnetic sensor in printed circuit board (PCB). The fluxgate sensor consists of five PCB stack layers including one layer magnetic core and four layers of excitation and pick-up coils. The center layer as a magnetic core is made of a micro patterned amorphous magnetic ribbon with extremely high DC permeability of ∼100,000 and the core has a rectangular-ring shape. The amorphous magnetic core is easily saturated due to the low coercive field and closed magnetic path for the excitation field. Four outer layers as an excitation and pick-up coils have a planar solenoid structure. The chip size of the fabricated sensing element is 7.3${\times}$5.7m㎡. Excellent linear response over the range of -100${\mu}$T to +100${\mu}$T is obtained with 540V/T sensitivity at excitation square wave of 3V$\_$P-P/ and 360kHz. The very low power consumption of ∼8mW was measured. This magnetic sensing element which measures the lower fields than 50${\mu}$T, is very useful for various applications such as: portable navigation systems, military research, medical research, and space research.

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Embedded Micro Fluxgate Sensor in Printed Circuit Board (PCB) (PCB 기판에 내장된 마이크로 플럭스게이트 센서)

  • 최원열;황준식;강명삼;최상언
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.8
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    • pp.702-707
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    • 2002
  • This paper presents a micro fluxgate sensor in printed circuit board (PCB). The fluxgate sensor consists of five PCB stack layers including one layer magnetic core and four layers of excitation and pick-up coils. The center layer as a magnetic core is made of a micro patterned amorphous magnetic ribbon and the core has a rectangular-ring shape. The amorphous magnetic core is easily saturated due to the low coercive field and closed magnetic path for the excitation field. Four outer layers as an excitation and pick-up coils have a planar solenoid structure. The chip size of the fabricated sensing element is 7.3$\times$5.7$\textrm{mm}^2$. Excellent linear response over the range of -100$\mu$T to +100$\mu$T is obtained with 540V/T sensitivity at excitation square wave of 3 $V_{p-p}$ and 360kHz. The very low power consumption of ~8mW was measured. This magnetic sensing element, which measures the lower fields than 50$\mu$T, is very useful for various applications such as: portable navigation systems, military research, medical research, and space research.h.

Properties of Filter type Magnetoimpedance Sensor (필터타입으로 구성한 자기임피던스센서의 특성)

  • SaGong, Geon;Kim, Young-Hak;Shin, Kwang-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.337-340
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    • 2004
  • To develop the highly sensitive Magneto-Impedance sensor, the amorphous ribbon was micro-processed to meander type sensor pattern and the filter circuit was constructed with this pattern. Its external magnetic field dependence of impedance and the output properties of the filter circuit were investigated. The impedance of the pattern had a peak value at the magnetic field of 10 Oe and its changing ratio was about 280%. The impedance change per unit magnetic field was about 36%, in which the output with high sensitivity and linearity could be obtained. The output sensitivity was about 7%/Oe at bias field of 6 Oe..

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Characteristics variation of CoCrTa/Si double layer thin film on variation of underlayer substrate temperature (하지층기판온도에 따른 CoCrTa/Si 이층박막의 특성변화)

  • Park, W.H.;Kim, Y.J.;Keum, M.J.;Ka, C.H.;Son, I.H.;Choi, H.W.;Kim, K.H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.77-80
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    • 2001
  • Crystallographic and magnetic characteristics of CoCr-based magnetic thin film for perpendicular magnetic recording media were influenced on preparing conditions. In these, there is that substrate temperature was parameter that increases perpendicular coercivity of CoCrTa magnetic layer using recording layer. While preparation of CoCr-based doublelayer, by optimizing substrate temperature, we expect to increase perpendicular anisotropy of CoCr magnetic layer and prepare ferromagnetic recording layer with a good quality by epitaxial growth. CoCrTa/Si doublelayer showed a good dispersion angle of c-axis orientation $\Delta\theta_{50}$ caused by inserting amorphous Si underlayer which prepared at underlayer substrate temperature 250C. Perpendicular coercivity was constant, in-plane coercivity was controlled a low value about 200Oe. This result implied that Si underlayer could restrain growth of initial layer of CoCrTa thin film, which showed bad magnetic properties effectively without participating magnetization patterns of magnetic layer. In case of CoCrTa/Si that prepared with ultra thin underlayer, crystalline orientation of CoCrTa was improved rather underlayer thickness 1nm, it was expected that amorphous Si layer played a important role in not only underlayer but also seed layer.

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Development of An Algorithm to Analyse Magnetic Field of Amorphous Core using Homogenization Technique (균질화 기법을 이용한 비정질 Core의 자개해석 Algorithm개발)

  • Lee, Jin-Hee;Shin, Pan-Seok
    • Proceedings of the KIEE Conference
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    • 1994.07a
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    • pp.79-81
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    • 1994
  • A solution of magnetic fields for amorphous core transformer has been tried using homogenization technique. The technique, which is derived by applying asymptotic expansion to the standard finite element method, is helpful to analyse a joint part of amorphous core transformer microscopically. A butt-lap-step joint type of lamination method is modeled and its equivalent reluctivity is calculated to analyse various quantities of the magnetic fields. The algorithm is also applicable to other electric devices which have complicated material structure with repeated patterns.

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The Magnetic Properties of $Fe_{87}Zr_{7}B_{5}Ag_{1}$(at.%) Amorphous Alloy ($Fe_{87}Zr_{7}B_{5}Ag_{1}$ 비정질합금의 연자기 특성)

  • 김병걸;송재성;김현식;오영우
    • Journal of the Korean Magnetics Society
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    • v.5 no.1
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    • pp.8-14
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    • 1995
  • The magnetic properties of an $Fe_{87}Zr_{7}B_{5}Ag_{1}$(at.%) amorphous alloy have been investigated as a function of annealing temperatures to clarify its application potential as a core material for high-frequency use by adding a small amount of insoluble element of Ag. A new excellent soft magnetic material was developed. The amorphous alloy produced by relatively low temperature annealing at $T_{a}=400^{\circ}C$ exhibited very high initial permeability$(\mu_{i})$ of 288,000 at 1kHz and 2mOe, very low coercivity$(H_{c})$ of 15mOe and low core loss$(W_{c})$ of 50W/kg at 100kHz and 1,000G which is comparable with Co-based amorphous alloys, respectively. It is notable that the values obtained in the present study are the best magnetic properties among various kinds of Fe-based soft amorphous materials reported up to date. The reasons for the achievement of good soft magnetic properties are presumably due to the homogeneous formation of very fine $\alpha$-Fe clusters with the size of 2~3nm in an amorphous matrix, which can be deduced from the increase of resistivity and the TEM observation. The very fine $\alpha$-Fe clusters embedded in an amorphous matrix had a great influence on reduction of magnetostriction and refinement of magnetic domain.

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Permeability of CoZrNb film with thickness (CoZrNb막의 두께에 따른 투자율의 변화)

  • Hoe, J.;Kim, Y.H.;Shin, K.H.;Sa-Gong, G.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.443-446
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    • 2001
  • MI(Magneto-Impedance) sensor which is made by thin films has significantly high detecting sensitivity in weak magnetic field. It also has a merit to be able to build in low power system. Its structure is simple, which makes it easier to prepare a miniature. In this study, its magnetic permeability and anisotropy field(H$\sub$k/) as a function of a thickness of sputtered amorphous CoZrNb thin film with high saturation magnetostriction and excellent soft magnetic property are investigated. In order to make a uniaxial anisotropy, thin film was subjected to post annealing with a static magnetic field with 1KOe intensity at 250, 300, and 320$^{\circ}C$ for 2 hour. Anisotropy field(H$\sub$k/)of thin film is measured by using MH loop tracer. Its magnetic permeability of thin film is measured over the frequency range from 1 MHz to 750MHz. It has shown that the magnetic permeability of amorphous CoZrNb thin film is decreased due to the skin effect with increasing a thickness of CoZrNb thin film, and hence its driving frequency is lowered.

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