• 제목/요약/키워드: Crystal grain size

검색결과 293건 처리시간 0.026초

기판에 따른 p-type $CuCrO_2$ 박막의 성장방향변화 (Orientation control of $CuCrO_2$ films on different substrate by PLD)

  • Kim, Se-Yun;Sung, Sang-Yun;Jo, Kwang-Min;Hong, Hyo-Ki;Lee, Joon-Hyung;Kim, Jeong-Joo;Heo, Young-Woo
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
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    • pp.142-142
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    • 2011
  • Epitaxial $CuCrO_2$ thin films have been grown on single crystal substrate of c-plane $Al_2O_3$, $SrTiO_3$, YSZ and Quarts by laser ablation of a $CuCrO_2$ target using 266nm radiation from a Nd:YAG laser. X-ray measurements indicate that the $CuCrO_2$ grows epitaxially on all substrate, with its orientation dependent on the kinds of substrates. Most of the layer were polycrystalline with (001), (015) and random as the dominant surface orientation on c-plane YSZ, $SrTiO_3$ and quarts substrate, respectively. (001) orientated $CuCrO_2$ grows on C-plane $Al_2O_3$ and YSZ substrate, (015) orientated $CuCrO_2$ films are found on c-plane $SrTiO_3$ substrate and random orientated $CuCrO_2$ films grows on quarts substrate. These data are compared with the in-plane orientation and the mismatch of the $CuCrO_2$ and each substrate lattices in an attempt to relate the preferred orientation to the plane of the sapphire on which it is grown. Further characterization show that the grain size of the films increases for a substrate temperature increase, whereas the electrical properties of $CuCrO_2$ thin films depend upon their crystalline orientation.

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이온빔 증착법에 의해 제조된 철박막의 미세조직 분석 (Microstructure Analysis of Fe Thin Films Prepared by Ion Beam Deposition)

  • 김가희;양준모;안치원;서현상;강일석;황욱중
    • 대한금속재료학회지
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    • 제46권7호
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    • pp.458-463
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    • 2008
  • High purity Fe thin films were prepared by the ion beam deposition method with $^{56}Fe^{+}$ions on the Si substrate at the room temperature. The Fe thin films were deposited at the ion energy of 50 eV and 100 eV. Microstructural properties were investigated on the atomic scale using high-resolution transmission electron microscopy (HRTEM). It was found that the Fe thin film obtained with the energy of 50 eV having an excellent corrosion resistance consists of the amorphous layer of ~15 nm in thickness and the bcc crystalline layer of about 30 nm in grain size, while the thin film obtained with the energy of 100 eV having a poor corrosion resistance consists of little amorphous layer and the defective crystalline layer. Furthermore the crystal structures and arrangements of the oxide layers formed on the Fe thin films were analyzed by processing of the HRTEM images. It was concluded that the corrosion behavior of Fe thin films relates to the surface morphology and the crystalline structure as well as the degree of purification.

LaNbO4:RE3+ (RE = Dy, Dy/Sm, Sm) 형광체의 구조, 표면, 광학 특성 (Structural, Morphological, and Optical Properties of LaNbO4:RE3+ (RE = Dy, Dy/Sm, Sm) Phosphors)

  • 이진홍;조신호
    • 한국표면공학회지
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    • 제51권5호
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    • pp.271-276
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    • 2018
  • The effects of activator ion on the structural, morphological, and optical properties of $LaNbO_4:RE^{3+}$ (RE = Dy, Dy/Sm, Sm) phosphors were investigated. X-ray diffraction patterns exhibited that all the phosphors showed a monoclinic system with a main (112) diffraction peak, irrespective of the concentration and type of activator ions. The grain size showed a slightly decreasing tendency as the concentration of $Sm^{3+}$ ions increased. The excitation spectra of the $LaNbO_4:Dy^{3+}$, $Sm^{3+}$ phosphor powders consisted of a strong charge transfer band centered at 259 nm in the range of 220-290 nm and five weak peaks. The emission spectra of the $La_{0.95}NbO_4$:5 mol% $Dy^{3+}$ phosphors exhibited two intense yellow and blue bands centered at 575 nm and 479 nm respectively, which resulted from the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ and $^4F_{9/2}{\rightarrow}^6H_{15/2}$ transitions of $Dy^{3+}$. As the concentration of $Sm^{3+}$ was increased, the intensity of the yellow emission band was gradually decreased, while those of orange and red emission bands centered at 604 and 646 nm began to appear and reached maxima at 5 mol%, and then decreased rapidly with further increases in the $Sm^{3+}$ concentration. These results indicated that white light emission could be realized by controlling the concentrations of the $Dy^{3+}$ and $Sm^{3+}$ ions incorporated into the $LaNbO_4$ host crystal.

BaTiO3 첨가에 따른 Bi1/2Na1/2TiO3-SrTiO3 무연 압전 세라믹스의 전기적 특성 및 상전이 거동 연구 (Electrical Properties and Phase Transition Behavior of Lead-Free BaTiO3-Modified Bi1/2Na1/2TiO3-SrTiO3 Piezoelectric Ceramics)

  • 강유빈;박재영;무클리사 아이샤 데비타;즈엉 짱 안;안창원;김병우;한형수;이재신
    • 한국전기전자재료학회논문지
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    • 제35권5호
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    • pp.516-521
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    • 2022
  • We investigated the microstructure, crystal structure, dielectric, and elecromechanical strain properties of lead-free BaTiO3 (BT)-modified (Bi1/2Na1/2)TiO3-SrTiO3 (BNT-ST) piezoelectric ceramics. Samples were prepared by a conventional ceramic processing route. Temperature dependent dielectric properties confirmed that a phase transition from a nonergodic relaxor to an ergodic relaxor was induced when the BT concentration reached 1.5 mol%, interestingly, where the average grain size reached a maximum value of 4.5 ㎛. At the same time, enhanced electromechanical strain (Smax/Emax = 600 pm/V) was obtained. It is suggested that the induced ferroelectric-relaxor phase transition by the BT modification is responsible for the enhancement of electromechanical strain in 1.5 mol% BT-modified BNT-ST ceramics.

열처리 온도가 SrWO4:Sm3+ 박막의 구조, 표면, 발광 특성에 미치는 효과 (Effects of Annealing Temperature on the Structural, Morphological, and Luminescent Properties of SrWO4:Sm3+ Thin Films)

  • 조신호
    • 한국전기전자재료학회논문지
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    • 제36권6호
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    • pp.582-587
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    • 2023
  • The effects of the annealing temperature on the structural, morphological, and luminescent properties of SrWO4:Sm3+ thin films grown on quartz substrates by radio-frequency magnetron sputtering were investigated. The thin films were annealed at various annealing temperatures for 20 min in a rapid thermal annealer after growing the thin films. The experimental results showed that the annealing temperature has a significant effect on the properties of the SrWO4:Sm3+ thin films. The crystal structure of the as-grown SrWO4:Sm3+ thin films was transformed from amorphous to crystalline after annealing at 800℃. The preferred orientation along (112) plane and a significant increase in average grain size by 820 nm were observed with increasing the annealing temperature. The average optical transmittance in the wavelength range of 500~1,100 nm was decreased from 72.0% at 800℃ to 44.2% at an annealing temperature of 1,000℃, where the highest value in the photoluminescence intensity was obtained. In addition to the red-shift of absorption edge, a higher annealing temperature caused the optical band gap energy of the SrWO4:Sm3+ thin films to fall rapidly. These results suggest that the structural, morphological, and luminescent properties of SrWO4:Sm3+ thin films can be controlled by varying annealing temperature.

산소 유입 없이 RF 스퍼터로 증착한 고품질 ITO 박막의 두께와 열처리 온도에 따른 박막의 특성 변화 (Effects of Film Thickness and Post-Annealing Temperature on Properties of the High-Quality ITO Thin Films with RF Sputtering Without Oxygen)

  • 성지하;김형민;신성민;김경환;홍정수
    • 한국전기전자재료학회논문지
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    • 제37권3호
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    • pp.253-260
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    • 2024
  • In this study, ITO thin films were fabricated on a glass substrate at different thicknesses without introducing oxygen using RF sputtering system. The structural, electrical, and optical properties were evaluated at various thicknesses ranging from 50 to 300 mm. As the thickness of deposited ITO thin film become thicker from 50 to 100 mm, carrier concentration, mobility, and band gap energy also increased while the resistivity and transmittance decreased in the visible light region. When the film thickness increased from 100 to 300 mm, the carrier concentration, mobility, and band gap energy decreased while the resistivity and transmittance increased. The optimum electrical properties were obtained for the ITO film 100 nm. After optimizing the thickness, the ITO thin films were post-annealed at different temperatures ranging from 100 to 300℃. As the annealing temperature increased, the ITO crystal phase became clearer and the grain size also increased. In particular, the ITO thin film annealed at 300℃ indicated high carrier concentration (4.32 × 1021 cm-3), mobility (9.01 cm2/V·s) and low resistivity (6.22 × 10-4 Ω·cm). This means that the optimal post-annealing temperature is 300℃ and this ITO thin film is suitable for use in solar cells and display application.

메틸트리클로로실란을 이용한 화학증착 탄화규소의 증착율 및 굽힘강도 특성에 미치는 온도의 영향 (Effect of Temperature on the Deposition Rate and Bending Strength Characteristics of Chemical Vapor Deposited Silicon Carbide Using Methyltrichlorosilane)

  • 송준백;임항준;김영주;정연웅;류희범;이주호
    • Composites Research
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    • 제31권2호
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    • pp.43-50
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    • 2018
  • 화학기상증착 탄화규소(CVD-SiC)의 높은 증착율과 우수한 굽힘강도 특성을 얻기 위해 증착온도에 대한 영향을 연구하였다. Hot-wall CVD 방법으로 메틸트리클로로실란(MTS : $CH_3SiCl_3$)을 이용하여 $1250{\sim}1400^{\circ}C$ 조건에서 제조된 탄화규소는 $95.7{\sim}117.2{\mu}m/hr$ 정도의 증착율을 보였다. 율속반응은 $1300^{\circ}C$ 미만에서는 표면반응, 그 이상의 온도에서는 물질전달 지배영역 특성을 나타내었다. Arrhenius plot을 통해 계산한 활성화 에너지는 각각 11.26 kcal/mole과 4.47 kcal/mole이였다. 증착온도별 표면 형상은 $1250^{\circ}C$ pebble에서 $1300^{\circ}C$ facet 구조로 변하였고, $1350^{\circ}C$ 이상에서는 multi-facet 구조를 나타내었다. 단면 형상은 $1300^{\circ}C$ 이하에서 columnar, $1350^{\circ}C$ 이상에서 isometric 구조를 보였다. 결정상은 모두 ${\beta}$-SiC로 확인되었지만 결정성장 방향은 $1250^{\circ}C$ (111)에서 $1300^{\circ}C$ 이상부터 (220) peak가 관찰되었으며, $1400^{\circ}C$에서는 (220)으로 완전히 변함을 알 수 있었다. 굽힘강도 특성은 증착온도가 증가할수록 치밀화되고, columnar에서 isometric 조직으로 변화되면서 $1350^{\circ}C$에서 최대값을 나타내었으며, $1400^{\circ}C$에서는 grain size 증가와 결정성장 방향이 최밀충진면인 (111)에서 (220)으로 완전히 변하면서 감소된 것으로 보인다.

코팅용 알루미타, 티타니아솔 제조에 관한 연구 (A Study on the Preparation of Aluina & Titania Sols for Coatings)

  • 김추희;최형수;조영상;임종주
    • 한국재료학회지
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    • 제4권3호
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    • pp.319-328
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    • 1994
  • 솔-제법에 의한 고분자솔 제조를 위하여 금속 알콕사이드에 $\beta$-diketonate(DKT)기의 유기 리간드를 치환시켜 만든 전구체를 합성한 결과, 가수분해와 축합 반응의 속도 조절이 가능하였고, 이를 이용하여 코팅에 적합한 nm단위의 입자 크기를 갖는 알루미나, 티타니아 솔을 제조하고 그 물성을 파악하였다. 코팅에 적합한 알루미나 솔의 최적조건은 알콕사이드 1몰당 물 1몰, 산 0.3-0.4몰이었다. 티타니아 솔의 제조시는 물/알콕사이드의 몰비가 1이고, 산의 양은 치환수에 따라 달라 1개와 2개 치환된 전구체의 경우 1목의 알콕사이드당 각각 0.25, 0.20몰 이하였다. Dynamic light scattering 장치를 이용하여 제조한 솔의 평균 입자 크기를 측정한 결과 수 nm단위의 미세한 입자를 갖고 있었다. 슬라이드 글라스 위에 코팅하여 $450^{\circ}C$에서 소결한 막을 SEM으로 관찰한 결과 알루미나와 타타니아의 경우 각각 4-4.5$\mu \textrm{m}$, 2-2.5$\mu \textrm{m}$두께의 매끄럽고 균열이 없는 막이 형성되었음을 알 수 있었다. 이때의 입자 크기는 TEM사진을 통하여 알 수 있었으며 티타니아의 경우 수 nm에서 최대 30nm, 알루미나는 1-2nm이하 심지어 수 $\AA$정도의 입자들로 이루어졌음을 관찰하였다. 또한 회절무늬 분석 결과 알루미나는 $\gamma$구조, 티타니아는 anastase결정임을 알 수 있었다.

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(Ba0.7Sr0.3-3x/2Lax)(Ti0.9Zr0.1)O3 세라믹의 Sr2+-자리에 대한 La3+ 치환에 따른 유전 특성 (Dielectric Properties of (Ba0.7Sr0.3-3x/2Lax)(Ti0.9Zr0.1)O3 Ceramics with La3+ Substitution for Sr2+-Site)

  • 김시현;김주혜;김응수
    • 한국재료학회지
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    • 제33권11호
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    • pp.465-474
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    • 2023
  • The effects of La3+ substitution for Sr2+-site on the crystal structure and the dielectric properties of (Ba0.7Sr0.3-3x/2Lax) (Ti0.9Zr0.1)O3 (BSLTZ) (0.005 ≤ x ≤ 0.02) ceramics were investigated. The structural characteristics of the BSLTZ ceramics were quantitatively evaluated using the Rietveld refinement method from X-ray diffraction (XRD) data. For the specimens sintered at 1,550 ℃ for 6 h, a single phase with a perovskite structure and homogeneous microstructure were observed for the entire range of compositions. With increasing La3+ substitution (x), the unit cell volume decreased because the ionic size of La3+ (1.36 Å) ions is smaller than that of Sr2+ (1.44 Å) ions. With increasing La3+ substitution (x), the tetragonal phase fraction increased due to the A-site cation size mismatch effect. Dielectric constant (εr) increased with the La3+ substitution (x) due to the increase in tetragonality (c/a) and the average B-site bond valence of the ABO3 perovskite. The BSLTZ ceramics showed a higher dielectric loss due to the smaller grain size than that of (Ba0.7Sr0.3)(Ti0.9Zr0.1)O3 ceramics. BSLTZ (x = 0.02) ceramics met the X7R specification proposed by the Electronic Industries Association (EIA).

화학적공침법에 의한 $A_{2}B_{2}O_{7}$ 고온압전세라믹스의 제작과 전기적 특성 (Fabrication and Electrical Properties of High Tc $A_{2}B_{2}O_{7}$ Piezoelectric Ceramics Using the Powders Prepared by the Chemical Coprecipitation Method)

  • 손창헌;전상재;남효덕
    • 센서학회지
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    • 제6권4호
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    • pp.316-327
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    • 1997
  • 높은 큐리온도를 가진 다결정 세라믹스 $Sr_{2}Nb_{2}O_{7}$$La_{2}Ti_{2}O_{7}$을 화학적공침법으로 제조하고 하소분말의 입도분포와 상구조 및 소결특성 등을 조사하였으며, 소결온도에 따른 입자배향도와 전기적 특성을 선행연구 고상반응법 및 용융염합성법과 비교하였다. 화학적공침법을 이용함으로써 고상반응법에 비해 $100{\sim}150^{\circ}C$ 낮은 하소온도에서 단일상을 얻을 수 있었고, 특히 $Sr_{2}Nb_{2}O_{7}$의 경우, $700^{\circ}C$에서 중간 생성물 $Sr_{5}Nb_{4}O_{15}$가 생성된 후 $800^{\circ}C$의 낮은 하소온도에서 단일상이 나타났으며 얻어진 하소분말도 미세하고 균일하였다. 화학적공침법에 의해 $1500^{\circ}C$에서 소결한 $Sr_{2}Nb_{2}O_{7}$ 세라믹스는 이론밀도의 97%에 달하는 우수한 소결성을 보였을 뿐만 아니라 (0k0) 방향의 입자배향도가 현저히 컸으며, 결과적으로 절단방향에 따른 유전특성의 이방성을 나타내어 a-cut 방향의 유전율은 단결정에 비해 손색이 없었다.

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