• Title/Summary/Keyword: Zn precursor

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Effects of Al3+ precipitation onto primitive amorphous Cu-Zn precipitate on methanol synthesis over Cu/ZnO/Al2O3 catalyst

  • Jeong, Cheonwoo;Park, Jongha;Kim, Jinsung;Baik, Joon Hyun;Suh, Young-Woong
    • Korean Journal of Chemical Engineering
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    • v.36 no.2
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    • pp.191-196
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    • 2019
  • The phase of Cu,Zn,Al precursors strongly affects the activity of their final catalysts. Herein, the Cu,Zn,Al precursor was prepared by precipitation of $Al^{3+}$ onto primitive, amorphous Cu,Zn precipitate. This precursor turned out to be a phase mixture of zincian malachite and hydrotalcite in which the latter phase was less abundant compared to the co-precipitated precursor. The final catalyst derived from this precursor exhibited a little higher copper surface area and methanol synthesis activity than the co-precipitated counterpart. Therefore, the two precursor phases need to be mixed in an adequate proportion for the preparation of active $Cu/ZnO/Al_2O_3$ catalyst.

Preparation of ZnO Thin Films Using Zn/O-containing Single Precursorthrough MOCVD Method

  • Park, Jong-Pil;Kim, Sin-Kyu;Park, Jae-Young;Ok, Kang-Min;Shim, Il-Wun
    • Bulletin of the Korean Chemical Society
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    • v.30 no.1
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    • pp.114-118
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    • 2009
  • A new Zn/O single source precursor, TMEDA-Zn$(eacac)_2$, has been synthesized by using N, N, N’, N’-tetramethylethylendiamine (TMEDA), sodium ethyl-acetoacetate, and $ZnCl_2$. From this organometallic precursor, ZnO thin films have been successfully grown on Si (100) substrates through the metal organic chemical vapor deposition (MOCVD) method at relatively mild conditions in the temperature range of 390~430 ${^{\circ}C}$. The synthesized ZnO films have been found to possess average grain sizes of about 70 nm with an orientation along the c-axis. The precursor and ZnO films are characterized through infrared spectroscopy, nuclear magnetic resonance spectroscopy, EI-FAB-spectroscopy, elemental analyses, thermal analysis, X-ray diffraction, and field emission scanning electron microscopic analyses.

Variations of Reaction Sequence with Precusor Mixing Methods in the Formation of $Pb(Zn_{0.6}Mg_{0.4})_{1/3}Nb_{2/3}O_3$[PZMN] ($Pb(Zn_{0.6}Mg_{0.4})_{1/3}Nb_{2/3}O_3$[PZMN] 합성시 전구체 혼합방법에 따른 반응 경로변화)

  • 김봉철;김정주;김남경;조상희
    • Journal of the Korean Ceramic Society
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    • v.35 no.5
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    • pp.458-464
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    • 1998
  • Variations of reaction sequence of $Pb(Zn_{0.6}Mg_{0.4})_{1/3}Nb_{2/3}O_3$[PZMN] with precusor mixing methods were ex-amined using X-ray diffraction and dielectric characteristics. In the present study three different types of precursor mixing methods (oxide mixing PbO+$ZnNb_2O_6+MgNb_2O_6$[Zn+MN] and PbO+(Zn,Mg)$Nb_2O_6$[ZMN] precursor mixing) were adopted. When the oxide mixing method was used for the PZMN synthesis a Zn-rich perovskite phase and pyrochlore phase were formed. Compared with PbO+ZN+MN precursor mixing method the PbO-ZMN precursor led to a lowering of the formation temperature for perovskite sin-gle phase. These variation of composition and formation temperature of the perovskite phase were dis-cussed in terms of the difference in the solid-reaction requence between these three different types of pre-cursor mixing.

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Characteristics of $ZnO_{x}$ films deposited by using zinc acetate as precursor (Zinc acetate를 precursor로 하여 증착한 $ZnO_{x}$막의 특성)

  • 마대영;김상현;이수철;김영진;김기완
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1994.11a
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    • pp.129-133
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    • 1994
  • $ZnO_{x}$ films were deposited by conventional thermal evaporation method. Zinc acetate was used as precursor. XRD and SEM results shows films as mixed stats of ZnO and zinc acetate. And EDX measurements reseal composition of films as $ZnO_{x}$.

Effects of Precursor Concentration on Surface and Optical Properties of ZnO Nano-Fibrous Thin Films Fabricated by Spin-Coating Method (스핀코팅 방법으로 제작된 ZnO 나노 섬유질 박막의 전구체 농도에 따른 표면 및 광학적 특성)

  • Kim, Min-Su;Kim, Ghun-Sik;Yim, Kwang-Gug;Cho, Min-Young;Jeon, Su-Min;Choi, Hyun-Young;Lee, Dong-Yul;Kim, Jin-Soo;Kim, Jong-Su;Lee, Joo-In;Leem, Jae-Young
    • Journal of the Korean Vacuum Society
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    • v.19 no.6
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    • pp.483-488
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    • 2010
  • ZnO nano-fibrous thin films with various precursor concentrations ranging from 0.2 to 1.0 mol (M) were grown by spin-coating method and effects of the precursor concentration on surface and optical properties of the ZnO nano-ribrous thin films were investigated by using scanning electron microscopy (SEM) and photoluminescence (PL). ZnO nuclei were formed at the precursor concentration below 0.4 M and the ZnO nano-fibrous thin films were grown at the precursor concentration above 0.6 M. Further increase in the precursor concentration, the thickness of the ZnO nano-fibrous thin films is gradually increased. The intensity and the full-width at half-maximum (FWHM) of the near-band-edge emission (NBE) is increased as the precursor concentration is increased. The deep-level emission (DLE) is red-shifted as the precursor concentration is increased.

Growth, Structural and Optical Properties of c-axis Oriented ZnO Nanorods Array by Hydrothermal Method (수열합성에 의한 c축 배향 ZnO 나노로드 배열의 성장과 구조, 광학적 특성)

  • Kim, Kyoung-Bum;Kim, Chang-Il;Jeong, Young-Hun;Lee, Young-Jin;Paik, Jong-Hoo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.3
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    • pp.222-227
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    • 2010
  • ZnO nanorods array have been grown on the seed crystal coated Si(100) substrate by hydrothermal method. The growth, structural and optical properties of ZnO nanorods array were investigated with a variation of precursor concentration from 0.01 M to 0.04 M. The array density of grown ZnO nanorods per same area was increased with increasing the concentration of precursor solution. Vertically aligned ZnO nanorods with hexagonal wurtzite structure have highly preferred c-axis orientation along (002) lattice plane. Especially, ZnO nanorods array developed from 0.04 M precursor solution showed a diameter of about 85 nm and length of 1.2 {\mu}m$ without any crystallographic defects. The photoluminescence spectra of ZnO nanorods from heavier precursor concentration exhibited stronger UV emission around 380 nm corresponding with near-band-edge emission.

Fabrication of Diameter-tunable Well-aligned ZnO Nanorod Arrays via a Sonochemical Route

  • Jung, Seung-Ho;Oh, Eu-Gene;Lee, Kun-Hong;Jeong, Soo-Hwan;Yang, Yo-Sep;Park, Chan-Gyung
    • Bulletin of the Korean Chemical Society
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    • v.28 no.9
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    • pp.1457-1462
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    • 2007
  • A simple and facile sonochemical route was described for the fabrication of diameter-controlled ZnO nanorod arrays on Si wafers. The diameter of ZnO nanorods was controlled by the concentration of zinc cations and hydroxyl anions in aqueous precursor solution. At high concentration of the precursor solution, thick ZnO nanorod arrays were formed. On the contrary, thin ZnO nanorod arrays were formed at low concentration of the precursor solution. The average diameter of ZnO nanorods varies from 40 to 200 nm. ZnO nanorod arrays with sharp tip were also fabricated by the step-by-step decrease in precursor solution concentration. The crystal structure and optical characteristics of ZnO nanorods were investigated by transmission electron microscopy, X-ray diffraction, and photoluminescence spectroscopy. Growth mechanism of ZnO nanorod arrays was also proposed.

The xps study of the Cu-Zn nanofiber

  • Jeong, Eunkang;Kang, Yujin;Park, Juyun;Kang, Yong-Cheol
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.236.2-236.2
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    • 2015
  • The copper-zinc(Cu-Zn) nanofiber was prepared by electrospinning method. The Cu/PVP (polyvinylpyrrolidone) and Zn/PVP precursor solutions were prepared by dissolution of copper sulfate and zinc acetate in methanol, respectively. The PVP was used to control the viscosity of the precursor solutions. The optimized ratio for the Cu/PVP and Zn/PVP nanofibers was determined separately. Then the suitable ratio of the precursor solutions was applied for fabrication of Cu/Zn/PVP nanofiber. For the electrospinning method, the precursor solutions were filled in a syringe. The distance between metallic needle on the syringe and collector was fixed at 16 cm and the voltage was applied on the tip was 13.0 kV. And the as-spun nanofiber was heated at 353K for removal of residual solvent. Then the heated nanofibers were calcined at 973K to decompose PVP. The obtained Cu, Zn, and Cu-Zn nanofibers were investigated with X-ray photoelectron spectroscopy (XPS) for the chemical properties, scanning electron microscopy (SEM) for the morphologies, and X-ray diffraction (XRD) to characterize the crystallinity and phase of nanofibers.

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Synthesis of zinc oxide nanoparticles via aqueous solution routes (수용액 합성법에 의한 ZnO 나노분말의 합성)

  • Koo, Jin Heui;Yang, Jun Seok;Cho, Soo Jin;Lee, Byeong Woo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.26 no.5
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    • pp.175-180
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    • 2016
  • ZnO nanoparticles were synthesized by aqueous preparation routes of a precipitation and a hydrothermal process. In the processes, the powders were formed by mixing aqueous solutions of Zn-nitrate hexahydrate ($Zn(NO_3)_2{\cdot}6H_2O$) with NaOH aqueous solution under controlled reaction conditions such as Zn precursor concentration, reaction pH and temperature. Single ZnO phase has been obtained under low Zn precursor concentration, high reaction pH and high temperature. The synthesized particles exhibited flakes (plates), multipods or rods morphologies and the crystallite sizes and shapes would be efficiently controllable by changing the processing parameters. The hydrothermal method showed advantageous features over the precipitation process, allowing the precipitates of single ZnO phase with higher crystallinity at relatively low temperatures below $100^{\circ}C$ under a wider pH range for the Zn precursor concentration of 0.1~1 M.

The Effect of Mg Precursors on Optical and Structural Characteristics of Sol-Gel Processed Mg0.3Zn0.7O Thin Films (졸-겔법으로 성장시킨 Mg0.3Zn0.7O 박막의 Mg 전구체의 종류에 따른 광학적·구조적 특성에 관한 연구)

  • Yeom, Ahram;Kim, Hong Seung;Jang, Nak Won;Yun, Young;Ahn, Hyung Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.33 no.3
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    • pp.214-218
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    • 2020
  • In this study, MgxZn1-xO thin films, which can be applied not only to active layers of light-emitting devices (LEDs), such as UV-LEDs, but also to solar cells, high mobility field-effect transistors, and power semiconductor devices, are fabricated using the sol-gel method. ZnO and Mg0.3Zn0.7O solution synthesized by the sol-gel method and the thin film were grown by spin coating on a Si (100) substrate and sapphire substrate. The solutions are synthesized by dissolving precursor materials in 2-methoxyethanol (2-ME) solvent, and then monoethanolamine (MEA) was added to the mixed solution as a sol stabilizer. Zinc acetate dihydrate is used as a ZnO precursor, while Mg nitrate hexahydrate and Mg acetate tetrahydrate are used as an MgO precursor. Then, the optical and structural characteristics of the fabricated thin films are compared. The molar concentration of the Zn precursor in the solvent is fixed at 0.3 M, and the amount of the Mg precursor is 30% of Mg2+/Zn2+. The optical characteristics are measured using an UV-vis spectrophotometer, and the transmittance of each wavelength is measured. Structural characteristics are measured using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Composition analyses are performed using energy dispersive X-ray spectroscopy (EDS). The Mg0.3Zn0.7O thin film was well formed at the ratio of the Mg precursor added regardless of the type of Mg precursor, and the c-axis of the thin film was decreased, while the band gap was increased to 3.56 eV.