• Title/Summary/Keyword: Ceramic deposition

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Fabrication and Characterization of Ferroelectric PFN Thin Film by Sol-Gel Processing (솔-젤법에 의한 강유전성 PFN 박막의 제조 및 특성평가)

  • 류재율;김병호;임대순
    • Journal of the Korean Ceramic Society
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    • v.33 no.6
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    • pp.665-671
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    • 1996
  • Ferroelectric Pb(Fe1/2Nb1/2)O3 thin films were successfully fabricated on ITO/Glass substrate by sol-gel proces-sing and characterized to determine the dielectric and electric properties. Viscosity of PEN sol measured to investigate rheological properties was 3.25 cP which was proper for coating. The sol also showed Newtonian behavior. RTA(Rapid Thermal Annealing) was used for the annealing of the thin film and 1200~1700$\AA$ thick PEN thin films were fabricated by repeating the intermediate and the final annealing. After the deposition of Pt as top electrode by vacuum evaporation dielectric and electric properties were measured. Dielectric properties of FFN thin film were enhanced by increasing the perovskite phase fraction with increasing the annealing temperature. Measured dielectric constant of 1700$\AA$ PFN thin film annealed at $650^{\circ}C$ was 890 at 1kHz Capacitatnce density and dielectric loss were 47 fF/${\mu}{\textrm}{m}$2 and 0.47 respectively. As a result of measuring Curie temperature PFN thin films had Curie point with a rang of 110~12$0^{\circ}C$ and showed broad dielectric peak at that point. Leakage current of the PFN thin films were increased with increasing the annealing tempera-ture.

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Effects of Oxygen Flow Ratio on the Crystallographic Orientation of NiO Thin Films Deposited by RE Magnetron Sputtering (RF 마그네트론 스퍼터링에 의한 NiO 박막 증착시 산소 유량비가 박막의 결정 배향성에 미치는 영향)

  • 류현욱;최광표;노효섭;박용주;박진성
    • Journal of the Korean Ceramic Society
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    • v.41 no.2
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    • pp.106-110
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    • 2004
  • Nickel oxide (NiO) thin films were prepared on Si(100) substrates at room temperature by RF magnetron sputtering using a NiO target. The effects of oxygen flow ratio for the plasma gas on the preferred orientation and surface morphology of the NiO films were investigated. Highly crystalline NiO film with (100) orientation was obtained when it was deposited in pure Ar gas. For NiO film deposited in pure O$_2$ gas, on the other hand, the orientation of the film changed from (100) to (111) and its deposition rate decreased. The origin of the preferred orientation of the films was discussed. NiO films also showed different surface morphologies and roughnesses with the oxygen flow ratio.

Decomposition of Carbon Dioxide Using Sr Ferrites with Various Compositions (다양한 조성의 Sr 페라이트를 이용한 CO2분해 반응 특성)

  • 신현창;최정철;정광덕;최승철
    • Journal of the Korean Ceramic Society
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    • v.40 no.2
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    • pp.191-197
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    • 2003
  • Sr ferrites with various compositions were applied to the decomposition of $CO_2$ to mitigate the greenhouse effect. In the reduction reaction of Sr ferrites up to 80$0^{\circ}C$, starting temperature was lower with increasing of Sr content in Sr ferrite. However, the reactivity was higher with decreasing Sr content. In the $CO_2$ decomposition reaction with reduced Sr ferrites, the amount of CO and C were depended on the ratio of Sr and Fe in Sr ferrite. With increasing Sr content. larger amount of C were deposited on the surface of ferrite. Therefore, in order to apply Sr ferrites for the decomposition of $CO_2$, it is necessary to control the ratio of Sr and Fe according to the conditions used.

Effects of Annealing Atmosphere on Crystallization and Electrical Properties in $YMnO_3$ Ferroelectric Thin Films ($YMnO_3$ 강유전 박막의 열처리 분위기가 결정화거동과 전기적 특성에 미치는 영향)

  • 윤귀영;김정석;천채일
    • Journal of the Korean Ceramic Society
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    • v.37 no.2
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    • pp.168-173
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    • 2000
  • YMnO3 thin films were prepared on Pt/Ti/SiO2/Si substrate by chemical solution deposition method. The films were crystallized by heat-treatment at 85$0^{\circ}C$ for 1 hour. Effects of an annealing atmosphere(O2, Ar, vacuum) on the crystallization behavior and electridcal properties were investigated. YMnO3 thin films annealed under Ar atmosphere showed a superior crystallinity and a very strong c-aix preferred-orientation which was a polar axis. Leakage current density of the films decreased with lowering oxygen partial pressure of the annealing atmosphere. C-V and P-E ferroelectric hysteresis were observed only in the thin film heat-treated under Ar atmosphere.In order to prepare YMnO3 thin films having both low leakage current and ferroelectricity, the annealing atmsphere should be kept under a proper oxygen partial pressure which was about 1 Pa in this work. Leakage current density at 1 volt, dielectric constant($\varepsilon$r), remanent polarization(Pr), and coercive field(Ec) were 1.7$\times$10-8 A/$\textrm{cm}^2$, 25, 1.08$\mu$C/$\textrm{cm}^2$, and 100 kV/cm, respectively.

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SiON/SiO2 Multilayer Deposited by PECVD for Low-Loss Waveguides (저손실 광도파로 제작을 위해 PECVD 법에 의해 증착된 SiON/SiO2 다층박막)

  • 김용탁;김동신;윤대호
    • Journal of the Korean Ceramic Society
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    • v.41 no.3
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    • pp.197-201
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    • 2004
  • SiO$_2$ and SiON thick films were deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) technique on silicon wafer (100) using SiH$_4$ and $N_2$O as precursor gases. In this work, the influence of rf power, and rf bias power on the optical and physical properties of SiO$_2$ and SiON thick films is presented. The refractive index decreases with increasing rf power, and rf bias power. The refractive index of the films varied from 1.4493 to 1.4952 at wavelength at 1552 nm, with increasing rf power, the nitrogen content decreases while the oxygen content increases, in a manner that the O/N ratio increases approximately linearly.

Tribology and Phase Evolution of Cr-Mo-N Coatings with Different Interlayer Condition (중간층 조건에 따른 Cr-Mo-N 막의 상형성 및 마찰마모 거동 연구)

  • Yang, Young-Hwan;Lyo, In-Woong;Park, Sang-Jin;Im, Dae-Sun;Oh, Yoon-Suk
    • Journal of the Korean institute of surface engineering
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    • v.44 no.6
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    • pp.269-276
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    • 2011
  • Phase evolution and tribological behavior of Cr-Mo-N multi compositional films with different interlayer were investigated. The films were deposited by hybrid PVD (Physical Vapor Deposition) system consisted of dc unbalanced magnetron (UBM) sputtering and arc ion plating (AIP) sources. A pure molybdenum (Mo) was used as sputtering target and also a pure Cr was used as AIP target to form the Cr-Mo-N films. Various growth planes were found, no textured surface, in all of the multi composition films. Maximum value of microhardness was measured in Cr-Mo-N film with Mo interlayer as 29 GPa. Composition film was mainly showed the aspect of the adhesive wear than CrN film. The friction coefficient was decreased from 0.6 for pure CrN coating to 0.35 for Cr-Mo-N film with Mo interlayer. This result may come from the formation of metal oxide tribo-layer which is known as solid lubricant during the wear test.

Fabrication of Nd-Substituted Bi4Ti3O12 Thin Films by Metal Organic Chemical Vapor Deposition and Their Ferroelectrical Characterization

  • Kim, Hyoeng-Ki;Kang, Dong-Kyun;Kim, Byong-Ho
    • Journal of the Korean Ceramic Society
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    • v.42 no.4
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    • pp.219-223
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    • 2005
  • A promising capacitor, which has conformable step coverage and good uniformity of thickness and composition, is needed to manufacture high-density non-volatile FeRAM capacitors with a stacked cell structure. In this study, ferroelectric $Bi_{3.61}Nd_{0.39}Ti_3O_{12}$ (BNdT) thin films were prepared on $Pt(111)/TiO_2/SiO_2/Si$ substrates by the liquid delivery system MOCVD method. In these experiments, $Bi(ph)_{3}$, $Nd(TMHD)\_{3}$ and $Ti(O^iPr)_{2}(TMHD)_{2}$ were used as the precursors and were dissolved in n-butyl acetate. The BNdT thin films were deposited at a substrate temperature and reactor pressure of approximately $600^{\circ}C$ and 4.8 Torr, respectively. The microstructure of the layered perovskite phase was observed by XRD and SEM. The remanent polarization value (2Pr) of the BNdT thin film was $31.67\;{\mu}C/cm^{2}$ at an applied voltage of 5 V.

Ferroelectric and Magnetic Properties of BiFeO3 Thin Films Deposited on SrTiO3 Substrate (SrTiO3기판 위에 증착한 BiFeO3박막의 강유전 및 자기적 특성)

  • Lee, Eun-Gu;Kim, Sun-Jae;Lee, Jae-Gab
    • Journal of the Korean Ceramic Society
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    • v.45 no.6
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    • pp.358-362
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    • 2008
  • $BiFeO_3$ films were hetero-epitaxially grown on $SrTiO_3$ substrate with a various orientation by pulse laser deposition. $BiFeO_3$ films grown on (111) $SrTiO_3$ substrate have a rhombohedral structure, identical to that of single crystals. On the other hand, films grown on (110) or (001) $SrTiO_3$ substrate are monoclinically distorted from the rhombohedral structure due to the epitaxial constraint. The easy axis of spontaneous polarization is close to [111] for the variously oriented films. Dramatically enhanced polarization and magnetization have been found for $BiFeO_3$ thin films grown on $SrTiO_3$ substrate comparing to that of $BiFeO_3$ crystals. The results are explained in terms of an epitaxially-induced transition between cycloidal and homogeneous spin states, via magneto-electric interactions.

Properties of the Natural and CVD Synthetic Diamonds for Identification (천연과 CVD 합성 다이아몬드의 감별을 위한 물성 연구)

  • Kim, Yunwoo;Song, Jeongho;Noh, Yunyoung;Song, Ohsung
    • Journal of the Korean Ceramic Society
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    • v.51 no.4
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    • pp.350-356
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    • 2014
  • Recently, Chemical Vapor Deposition (CVD) synthetic diamonds have been introduced to the jewelry gem market, as CVD technology has been making considerable advances. Unfortunately, CVD diamonds are not distinguishable from natural diamonds when using the conventional gemological characterization method. Therefore, we need to develop a new identification method that is non-destructive, fast, and inexpensive. In our study, we employed optical microscopy and spectroscopy techniques, including Fourier transform infra-red (FT-IR), UV-VIS-NIR, photoluminescence (PL), micro Raman, and cathodoluminescent (CL) spectroscopy, to determine the differences between a natural diamond (0.30 cts) and a CVD diamond (0.43 cts). The identification of a CVD diamond was difficult when using standard gemological techniques, UV-VIS-NIR, or micro-Raman spectroscopy. However, a CVD diamond could be identified using a FT-IR by the Type II peaks. In addition, we identified a CVD diamond conclusively with the uneven UV fluorescent local bands, additional satellite PL peaks, longer phosphorescence life time, and uneven streaks in the CL images. Our results suggest that using FT-IR combined with UV fluorescent images, PL, and CL analysis might be an appropriate method for identifying CVD diamonds.

Synthesis and Characterization of ZnS and ZnS/TiO2 Nanocomposites and Their Enhanced Photo-decolorization of MB and 1,5-Diphenyl Carbazide

  • Meng, Ze-Da;Ullah, Kefayat;Zhu, Lei;Ye, Shu;Oh, Won-Chun
    • Journal of the Korean Ceramic Society
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    • v.51 no.4
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    • pp.307-311
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    • 2014
  • ZnS and $ZnS/TiO_2$ were prepared by chemical deposition. The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy (TEM). The generation of reactive oxygen species was detected by monitoring the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). Excellent catalytic degradation of methylene blue (MB) solution was observed using the $ZnS/TiO_2$ composites during irradiation with visible light. The results show that the photocatalytic performance of $TiO_2$ nanoparticles is improved by loading with ZnS.