• Title/Summary/Keyword: NbC

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Devised New Amorphous Alloys for Magneetoelastic Resonators (Magneetoelastic Resonators에 사용되는 새로운 비정질 함금)

  • C. K. Kim; C. K. Yoo; R.C. O'Handley
    • Journal of the Korean institute of surface engineering
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    • v.31 no.5
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    • pp.245-250
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    • 1998
  • There is clear pressing need to reduce bias field(Ha,) used on linear magenetomechanical resonator tag by at least a factor of two to allow low-bias operation near the frequency minimum since reducing Ha causes a dramatic increase in well depth, which implies increased stability. However, this makes it more difficult to maintain tight frequncy specs. It can be solved by a reduction of magnetomechanical coupling(k). We determined from an equivalent circuit model that optimal reduced, k, is near 0.3 Also, We determiend the material properties($lambda_s$, :saturated magenetostriction, $M_s$, and,$H_a$) that give k=0.3. From these evaluations, we suggested that on optimal comosition with adequate mathrial properties is $Fe_{55}Co_{15}Cr_6Nb_2B_{18}Si_4$.

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Effects of Particle Size on Properties of PZT -Based Thick Films (입자 크기가 PZT계 압전 후막의 물성에 미치는 영향)

  • 김동명;김정석;천채일
    • Journal of the Korean Ceramic Society
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    • v.41 no.5
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    • pp.375-380
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    • 2004
  • Pb(Ni$\_$1/3/Nb$\_$2/3/)O$_3$-PbZrO$_3$-PbTiO$_3$ thick films were screen-printed on platinized alumina substrates and fired at 800-1000$^{\circ}C$. Two kinds of powders with different particle size were prepared by attrition and ball milling methods. Effects of particle size of starting material on the microstructure and electrical properties of the thick films were investigated. Average particle size of attrition milled-powder (0.44 ${\mu}$m) was much smaller than that of ball milled-powder (2.87 ${\mu}$m). Average grain size of the thick film prepared from attrition-milled powder was smaller than that of the thick film prepared from ball-milled powder at the sintering temperature of 800$^{\circ}C$. However, the difference in average particle size became smaller with increasing the sintering temperature. Thick films prepared from attrition-milled powders showed more uniform and denser microstructures at all firing temperatures. Thick films prepared from attrition-milled powders had better electrical properties at the firing temperature above 900$^{\circ}C$ than thick films prepared from ball-milled powders. Dielectric constant, remanent polarization and coercive field of the thick film prepared from attrition-milled powders and fired at 900$^{\circ}C$ were 559, 16.3 ${\mu}$C/cm$^2$, and 51.3 kV/cm, respectively.

Fabrication of Doped BaTiO3 by Coprecipitation Method (공침법에 의한 반도성 BaTiO3 제조)

  • 안영필;김복희;이태석
    • Journal of the Korean Ceramic Society
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    • v.25 no.4
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    • pp.315-320
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    • 1988
  • The Nb doped BaTiO3 was synthesized by coprecipitation method using H2O2 media in region from pH 8 to pH 11. The powder prepared by using this method was crystallized at about 20$0^{\circ}C$ and average particle size was controlled by heat treatment. Because of preparation having fine particle and relatively narrow particle size distribution, high performance PTC device was made of these precipitated powders.

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열처리온도에 따른 SBN 세라믹 박막의 특성

  • Kim, Jin-Sa;Song, Min-Jong;Park, Geon-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.90-90
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    • 2009
  • The $Sr_{0.7}Bi_{2.3}Nb_2O_9$(SBN) thin films are deposited on Pt-coated electrode($Pt/Ti.SiO_2/Si$) using RF sputtering method. The dielectric constant of SBN thin films were increased with the increase of annealing temperature. The maximum dielectric constant of SBN thin film is obtained by annealing at 700[$^{\circ}C$]. The dielectric constant and dielectric loss had a stable value within -5~+5[V].

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