• Title/Summary/Keyword: X-ray diffraction patterns

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Synthesis and Characterization of One-Dimensional GaN Nanostructures Prepared via Halide Vapor-Phase Epitaxy

  • Byeun, Yun-Ki;Choi, Do-Mun;Han, Kyong-Sop;Choi, Sung-Churl
    • Journal of the Korean Ceramic Society
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    • v.44 no.3 s.298
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    • pp.142-146
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    • 2007
  • High-quality one-dimensional GaN nanorods and nanowires were synthesized on Ni-coated c-plan sapphire substrate using halide vapor-phase epitaxy (HVPE). Their structure and optical properties were investigated by X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence techniques. Full substrate coverage of densely packed, uniform, straight and aligned one-dimensional GaN nanowires with a diameter of 80nm were grown at $700{\sim}900^{\circ}C$. The X-ray diffraction patterns, transmission electron microscopic image, and selective area electron diffraction patterns indicate that the one-dimensional GaN nanostructures are a pure single crystalline and preferentially oriented in the [001] direction. We observed high optical quality of GaN nanowires by photoluminescence analysis.

Effect of Cu substitution on Superconductivity in $(Ru_{1-x}Cu_x)Sr_2(Eu_{1.34}Ce_{0.66})Cu_2O_z$ System (Cu 치환에 따른 $(Ru_{1-x}Cu_x)Sr_2(Eu_{1.34}Ce_{0.66})Cu_2O_z$ 계의 초전도 특성)

  • Lee, H.K.
    • Progress in Superconductivity
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    • v.11 no.1
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    • pp.67-71
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    • 2009
  • The effect of Cu substitution on the structural and superconducting properties of the $(Ru_{1-x}Cu_x)Sr_2(Eu_{1.34{\cdot}}Ce_{0.66})Cu_2O_z$ system with x = 0, 0.25 and 0.5 prepared under ambient pressure have been investigated. The X-ray diffraction patterns indicated that the Ru ions are replaced by the Cu ions. It is found that the Cu substitution for Ru significantly reduces the ferromagnetic component of field-cooled magnetic susceptibility, but results in a small change in diamagnetic onset transition temperature of zero-field-cooled magnetic susceptibility. In contrast to the Ru $Sr_2(Eu_{1.34{\cdot}}Ce_{0.66})Cu_2O_z$, bulk Meissner effect is observed in the field-cooled magnetization measurements of the Cu doped samples. The experimental results are discussed in connection with the spontaneous vortex phase interpretation.

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Growth of GaN Thin-Film from Spin Coated GaOOH Precursor (GaOOH 선구체의 스핀코팅에 의한 GaN 박막의 성장)

  • Lee, Jae-Bum;Kim, Seon-Tai
    • Korean Journal of Materials Research
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    • v.17 no.1
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    • pp.1-5
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    • 2007
  • GaN thin fan were grown by spin coated colloidal GaOOH precursor. Polycrystalline GaNs with crystalline size of $10{\sim}100nm$ were grown on $SiO_2$ substrate. The shape of crystallite above $900^{\circ}C$ had the hexagonal plate and column type. X-ray diffraction patterns for them correspond to those of the hexagonal wurtzite GaN. With increasing droplets. i.e, thickness of deposited layers, XRD intensity increased. PL (photoluminescence) spectrum consisted with an weak near band-edge emission at 3.45 eV and a broad donor-acceptor emission band at 3.32 eV. From the low temperature PL measurement on GaN grown at $800^{\circ}C$ that the shallow donor-acceptor recombination induced emission was more intense than the near band-edge excitonic emission.

The Microstructure and Mechanical Properties of Y2O3-Dispersed Fe-C and Fe-CNT Sintered Steels (Y2O3가 분산된 Fe-C 및 Fe-CNT 소결체의 미세구조 및 기계적 특성)

  • Lim, Jin Young;Ahn, Jung-Ho
    • Journal of Powder Materials
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    • v.24 no.4
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    • pp.298-301
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    • 2017
  • In the present work, we use multiwall carbon nanotubes (MWCNT) as the starting material for the fabrication of sintered carbon steel. A comparison is made with conventionally sintered carbon steel, where graphite is used as the starting material. Milling is performed using a horizontal mill sintered in a vacuum furnace. We analyze the grain size, number of pores, X-ray diffraction patterns, and microstructure. Changes in the physical properties are determined by using the Archimedes method and Vickers hardness measurements. The result shows that the use of MWCNTs instead of graphite significantly reduces the size and volume of the pores as well as the grain size after sintering. The addition of $Y_2O_3$.to the Fe-MWCNT samples further inhibits the growth of grains.

Catalytic performance of Al-MCM-48 molecular sieves in the isopropylation of phenol with isopropyl acetate (isopropyl acetate을 이용한 페놀의 isopropylation 반응의 Al-MCM-48 분자체 촉매반응 특성)

  • Venkatachalam, Kandan;Hemalatha, Pushparaj;Peng, Mei-Mei;Jang, Hyun-Tae
    • Proceedings of the KAIS Fall Conference
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    • 2011.05a
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    • pp.144-146
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    • 2011
  • Al-MCM-48 molecular sieves (Si/Al = 25, 50, 75 and 100) were synthesized hydrothermally using cetyltrimethyl ammonium bromide as the structure directing template. The orderly arrangement of mesopores was evident from the low angle X-ray diffraction patterns and TEM images. The catalytic performance was evaluated in the vapour phase isopropylation of phenol with isopropyl acetate. Phenol conversion decreased with increase in the Si/Al ratio of the catalysts. The major reaction product was 4-isopropyl phenol (selectivity: 78%). Delocalization of phenolic oxygen electron pair over the aromatic ring promoted para-selective alkylation. Such delocalization could be aided by the hydrophilic surface of the molecular sieves. Though ester was used as the alkylating agent, phenyl isopropyl ether was not formed

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Chloride ion removal effect for the ACF electrochemically treated with silver

  • Oh, Won-Chun;Park, Choung-Sung;Bae, Jang-Soon
    • Analytical Science and Technology
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    • v.19 no.4
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    • pp.316-322
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    • 2006
  • The removal efficiencies of silver-ACFs were associated with their surface properties such as surface area, porosity, and the electro-chemical reaction time for the silver treatments. X-ray diffraction patterns of fibers electrochemically treated with silver display diffraction peaks for metallic silver and kinds of silver chloride complexes on the fiber surface after electrochemical adsorption. The results of SEM and EDX indicate that surface reaction motive of silver-ACF prepared by electrochemical reaction are depend on time function for the chloride ion removal efficiency. Finally, Cl ion adsorbed by the silver-ACFs from the ICP analysis seems to show an excellent removal effect.

Optical and Electrochemical Properties of LiNiPO4 Thin Film for Transparent Thin Film Lithium Secondary Battery (투명 박막 리튬이차전지를 위한 LiNiPO4 박막의 광학 및 전기화학적 특성)

  • Lee, HyunSeok;Parmar, Narendra S.;Kim, Kwang-Bum;Choi, Ji-Won
    • Journal of Sensor Science and Technology
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    • v.27 no.1
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    • pp.36-39
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    • 2018
  • Transparent olivine $LiNiPO_4$ thin films on sapphire substrates were fabricated by radio frequency (RF) magnetron sputtering. The X-ray diffraction patterns show these thin films have the phase of $LiNiPO_4$ with an ordered olivine structure indexed to the orthorhombic Pmna space group. $LiNiPO_4$ thin films deposited on sapphire substrates exhibit transmittance of about 83 %. It was confirmed that the $LiNiPO_4$ thin film exhibits a high potential of 5 V-class.

Recycling of PET Bottle by Glycolysis in situ Transesterification (해중합 반응과 에스테르 교환반응의 동시 실행에 의한 PET병의 재활용)

  • Lee, Su-Bok;Choe, U-Sik
    • Textile Science and Engineering
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    • v.34 no.2
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    • pp.77-84
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    • 1997
  • Depolymerisation of post-consumed PET bottle during in situ transesterification with BMT and EG was studied and the kinetics of transesterification, thermal, mechanical properties of samples prepared at different PET scrap contents were investigated. Transesterification conyersion, calculated from effluent methanol, decreased as PET scrap content increased in the reaction mixture. The mechanical properties of PET prepared with 20, 3owt% PET scrap were similar to the original PET but decreased at PET scrap content of 40w1ole and in the case of ORP. Thermal properties were similar to original PET at all PET scrap contents. Intrinsic viscosity was found to decrease at 40% and ORP but found to be higher in other cases. X-ray diffraction patterns of bottle and samples containing PET showed different peaks from the original PET.

Dependence of ambient gas of oxide films fabricated by laser ablation method (레이저 어브레이션법에 의해 제조된 산화물 박막의 분위기가스 의존성)

  • 최충석;이덕출
    • Electrical & Electronic Materials
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    • v.9 no.4
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    • pp.357-363
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    • 1996
  • The superconducting properties of YBa$_{2}$Cu$_{3}$$O_{7-x}$(YBaCuO) thin films prepared by laser ablation have been investigated. The x-ray diffraction patterns of the films were substantially different from one another. The Y and Ba oxides are formed by the collisions with oxygen molecules. On the other hand, the Cu oxide is mainly formed at initial stage of the laser irradiation. The YBaCuO films manufactured on MgO(100) substrate were indicated T$_{c}$(zero)=90 K, T$_{c}$(onset)=92 K, and J$_{c}$=3.5*10$^{5}$ A/cm$^{2}$(at 77.3K). The optimum conditions were found to be a substrate temperature of 710.deg. C, an energy density of 2 J/cm$^{2}$, and a target-substrate distance of 60mm in an oxygen partial pressure of 200 mTorr.0 mTorr.

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Preparation and Characterization of Biopolymer-Based Nanocomposite Films: Chitosan-Based Nanocomposite Films with Antimicrobial Activity

  • Rhim, Jong-Whan
    • 한국포장학회:학술대회논문집
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    • 2006.11a
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    • pp.54-73
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    • 2006
  • Four different types of chitosan-based nanocomposite films were prepared using a solvent casting method by incorporating with four types of nanoparticles, i.e., an unmodified montmorillonite (Na-MMT), an organically modified montmorillonite (Cloisite 30B), a Nano-silver, and a Ag-zeolite (Ag-Ion). X-ray diffraction patterns of the nanocomposite films indicated that a certain degree of intercalation was formed in the nanocomposite films, with the highest intercalation in the Na-MMT-incorporated films followed by films with Cloisite 30B and Ag-Ion. SEM micrographs showed that in all the nanocomposite films, except the Nanosilver-incorporated one, nanoparticles were dispersed homogeneously throughout the chitosan polymer matrix. Consequently, mechanical and barrier properties of chitosan films were affected through intercalation of nanoparticles, i.e., tensile strength (TS) increased by 7-16%, while water vapor permeability (WVP) decreased by 25-30% depending on the nanoparticle material tested. In addition, chitosan-based nanocomposite films, especially silver-containing ones, showed a promising range of antimicrobial activity.

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