• 제목/요약/키워드: Nano ceramic

검색결과 731건 처리시간 0.028초

Fabrication and Properties of Porous Ni Thin Films

  • Choi, Sun-Hee;Kim, Woo-Sik;Kim, Sung-Moon;Lee, Jong-Ho;Son, Ji-Won;Kim, Joo-Sun
    • 한국세라믹학회지
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    • 제43권5호
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    • pp.265-269
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    • 2006

  • We have deposited NiO films by RF sputtering on $Al_2O_3/SiO_2/Si$ and 100 nm-thick Gd doped $CeO_2$ covered $Al_2O_3/SiO_2/Si$ substrates at various $Ar/O_2$ ratios. The deposited films were reduced to form porous Ni thin fllms in 4% $H_2\;at\;400^{\circ}C$. For the films deposited in pure Ar, the reduction was retarded due to the thickness and the orientation of the NiO films. On the other hand, the films deposited in oxygen mixed ambient were reduced and formed porous Ni films after 20 min of reduction. We also investigated the possibility of using the films for the single chamber operation by studying the electrical property of the films in the fuel/air mixed environment. It is shown that the resistance of the Ni film increases quickly in the mixed gas environment and thus further improvements of Ni-base anodes are required for using them in the single chamber operation.

  • https://doi.org/10.4191/KCERS.2006.43.5.265 인용 PDF KSCI

Use of Wet Chemical Method to Prepare β Tri-Calcium Phosphates having Macro- and Nano-crystallites for Artificial Bone

  • Chang, Myung Chul
    • 한국세라믹학회지
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    • 제53권6호
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    • pp.670-675
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    • 2016

  • Calcium phosphate crystallites were prepared by wet chemical method for use in artificial bone. In order to obtain ${\beta}$-tricalcium phosphate (TCP), nano-crystalline calcium phosphate (CaP) was precipitated at $37^{\circ}C$ and at $pH5.0{\pm}0.1$ under stirring using highly active $Ca(OH)_2$ in DI water and an aqueous solution of $H_3PO_4$. The precipitated nano-crystalline CaP solution was kept at $90^{\circ}C$ for the growth of CaP crystallites. Through the growing process of CaP crystallites, we were able to obtain various sizes of rectangular CaP crystallites according to the crystal growing times. Dry nano-crystalline CaP powders at $37^{\circ}C$ were mixed with dry macro-crystalline CaP crystallites and the shaped mixture sample was fired at $1150^{\circ}C$ to make a ${\beta}-TCP$ block. Several tens of nm powders were uniformly coated on the surface, which was comprised of powders of several tens of ${\mu}m$, using a vibrator. The mixing ratio between the nanometer powders and the micrometer powders greatly affected the mechanical strength of the mixture block; the most appropriate ratio of these two materials was 50 wt% to 50 wt%. The sintered block showed improved mechanical strength, which was caused by the solid state interaction between the nano-crystalline ${\beta}-TCP$ and the macro-crystalline ${\beta}-TCP$.

  • https://doi.org/10.4191/kcers.2016.53.6.670 인용 PDF KSCI

Effect of dopants(Tri-valent, Penta-valent) on the electrical and optical properties of SnO2 based transparent electrodes

  • Kim, G.W.;Sung, C.H.;Seo, Y.J.;Park, K.Y.;Heo, S.N.;Lee, S.H.;Koo, B.H.
    • Journal of Ceramic Processing Research
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    • 제13권spc2호
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    • pp.394-397
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    • 2012

  • In this work, we studied the influence of the dopant elements concentration on the properties of SnO2 thin films deposited by pulsed laser deposition. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Hall effect measurement and UV-Vis studies were performed to characterize the deposited films. XRD results showed that the films had polycrystalline nature with tetragonal rutile structure. FE-SEM micrographs revealed that the as deposited films composed of dense microstructures with uniform grain size distribution. All the films show n-type conduction and the best transparent conductive oxide (TCO) performance was obtained on 6 wt% Sb2O5 doped SnO2 film prepared at pO2 of 60mtorr and Ts of 500 ℃. Its resitivity, optical transmittance, figure of merit are 7.8 × 10-4 Ω cm, 85% and 1.2 × 10-2 Ω-1, respectively.

  • KSCI