• Title, Summary, Keyword: Zinc nitrate hexahydrate

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Effects of Precursor Concentration on the Growth of ZnO Nanorods (ZnO 나노로드 성장에 미치는 전구체 농도의 영향)

  • Ma, Tae-Young
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.11
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    • pp.1835-1839
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    • 2016
  • In this study, ZnO nanorods were grown by a hydrothermal method. $SiO_2/Si$ wafers and glass were used as substrates. ~20 nm-thick ZnO thin films were rf magnetron sputtered for seed layers. The precursor was prepared by mixing zinc nitrate hexahydrate and hexamethylenetetramine (hexamine) in DI water. The concentration of zinc nitrate hexahydrate was fixed at 0.05 mol, and that of hexamine was varied between 0 mol to 0.1 mol. The reactor containing substrates and precursor was put in an oven maintained at $90^{\circ}C$ for 1 h. X-ray diffraction was carried out to analyze the crystallinity of ZnO nanorods, and a field emission scanning electron microscope was employed to observe the morphology of nanorods. Transmittance and absorbance were measured by a UV-Vis spectrophotometer. Photoluminescence measurements were conducted using 266 nm light.

Reduction of Nitroarenes with Hydrazine Monohydrate by Activated Nickel Nitrate-Zinc Catalyst (히드라진과 질산니켈-아연과의 반응에서 얻은 활성화시킨 촉매를 이용한 방향족 니트로화합물의 환원)

  • Yun, Tae Ho;Pyo, Sang Hyeon;Park, Mun Gyu;Han, Byeong Hui
    • Journal of the Korean Chemical Society
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    • v.38 no.5
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    • pp.397-403
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    • 1994
  • An activated catalyst prepared from a mixture of nickel nitrate hexahydrate with zinc in dry ethanol under reflux showed exceptional catalytic activity for the reduction of nitroarenes to the corresponding azoxy compounds exclusively in the presence of hydrazine monohydrate. However, when nickel nitrate hexahydrate was replaced by nickel chloride dihydrate with zinc, only the aminoarenes were formed in high yields. With unactivated catalyst, the reduction reaction from a mixture of nitroarenes, nickel nitrate or chloride, excess zinc and hydrazine monohydrate gave the corresponding azo, azoxy and amino compounds in much lower yields.

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Effects of Boron Concentration in ZnO:Al Seed Films on the Growth and Properties of ZnO Nanorods (ZnO:Al 시드 막의 보론 농도가 ZnO 나노로드의 성장 및 특성에 미치는 영향)

  • Ma, Tae-Young;Park, Ki-Cheol
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.10
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    • pp.1488-1493
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    • 2017
  • Boron-doped ZnO:Al films were deposited by rf magnetron sputtering. The structural and optical property variations of the films with the boron amounts were studied. ZnO nanorods were grown on $SiO_2/Si$ wafers and glass by a hydrothermal method. ~50 nm-thick boron-doped ZnO:Al films were deposited on the substrates as seed layers. The mixed solution of zinc nitrate hexahydrate and hexamethylenetetramine in DI water was used as a precursor for ZnO nanorods. The concentration of zinc nitrate hexahydrate and that of hexamethylenetetramine were 0.05 mol, respectively. ZnO nanorods were grown at $90^{\circ}C$ for 2 hours. X-ray diffraction was conducted to observe the crystallinity of ZnO nanorods. A field emission scanning electron microscope was employed to study the morphology of nanorods. Optical transmittance was measured by a UV-Vis spectrophotometer, and photoluminescence was carried out with 266 nm light. The ZnO nanorods grown on the 0.5 wt% boron-doped ZnO seed layer showed the best crystallinity.

Annealing Effects of Seed Layers on the Properties of ZnO Nanorods (ZnO 나노로드 특성에 미치는 시드 막 열처리 영향)

  • Ma, Tae-Young;Park, Ki-Cheol
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.6
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    • pp.753-758
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    • 2018
  • We investigated annealing effects of seed layers on the properties of ZnO nanorods grown on the seed layers. ZnO nanorods were grown by a hydrothermal method. ~100 nm-thick ZnO films were sputtered on oxidized Si wafers and quartz as seed layers. The ZnO films were annealed at $400^{\circ}C$, $600^{\circ}C$, and $800^{\circ}C$, respectively. ZnO nanorods were grown at $90^{\circ}C$ for 3 hours in the mixed solution of zinc nitrate hexahydrate and hexamethylenetetramine. X-ray diffraction was carried out to estimate the crystallinity and strain of ZnO films and nanorods. A field emission scanning electron microscope was employed to observe the morphology of the films and nanorods. PL(photoluminescence) measurements were conducted with 266 nm light. It was found that the annealing of seed layers increase the growth rate of nanorods, and change compressive strain of nanorods to tensile strain. The intensity of PL in the UV region reduced by using the annealed seed layers.

Variation of Structural and Optical Properties of ZnO Nanorods with Growing Time (성장시간에 따른 ZnO 나노로드의 구조적 및 광학적 특성 변화)

  • Ma, Tae-Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.12
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    • pp.841-846
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    • 2016
  • ZnO nanorods were grown on $SiO_2$ coated Si wafers and glass by the hydrothermal method. The structural and optical properties variation of ZnO nanorods as a function of growing time was studied. ~10 nm-thick ZnO thin films deposited on substrates by rf magnetron sputtering were employed as seed layers. Zinc nitrate hexahydrate (0.05 M) and hexamethylenetetramine (0.05 M) mixed in DI water were used as a reaction solution. ZnO nanorods were respectively grown for 30 min, 1 h, 2 h, 3 h, and 4 h by maintaining the reactor at $90^{\circ}C$. Crystallinity of ZnO nanorods was analyzed by X-ray diffraction, and the morphology of nanorods was observed by a field emission scanning electron microscope. Transmittance and absorbance were measured by a UV-Vis spectrophotometer, and energy band gap and urbach energy were obtained from the data. Photoluminescence measurements were carried out using Nd-Yag laser (266 nm).

Fabrication and Thermophysical Properties of Al2O3-Based Multicomponent Composites by Sol-Gel Process (알루미나가 포함된 복합산화물의 제조와 열물성 특성평가)

  • Lim, Saet-Byeol;You, Hee-Jung;Hong, Tae-Whan;Jung, Mie-Won
    • Korean Journal of Materials Research
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    • v.20 no.9
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    • pp.472-477
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    • 2010
  • $Al_2O_3$ has received wide attention with established use as a catalyst and growing application in structural or functional ceramic materials. On the other hand, the boehmite (AlO(OH)) obtained by sol-gel process has exhibited a decrease in surface area during phase transformation due to a decline in surface active site at high temperature. In this work, $Al_2O_3$-CuO/ZnO (ACZ) and $Al_2O_3$-CuO/CeO (ACC) composite materials were synthesized with aluminum isopropoxide, copper (II) nitrate hemi (pentahydrate), and cerium (III) nitrate hexahydrate or zinc (II) nitrate hexahydrate. Moreover, the Span 80 as the template block copolymer was added to the ACZ/ACC composition to make nano size particles and to keep increasing the surface area. The ACZ/ACC synthesized powders were characterized by Thermogravimetry-Differential Thermal analysis (TG/DTA), X-ray Diffractometer (XRD), Field-Emmision Scanning Electron Microscope (FE-SEM), Bruner-Emmett-Teller (BET) surface analysis and thermal electrical conductivity (ZEM-2:M8/L). An enhancement of surface area with the addition to Span 80 surfactant was observed in the ACZ powders from 105 $m^2$/g to 142 $m^2$/g, and the ACC powders from 103 $m^2$/g to 140 $m^2$/g, respectively.

Methane Gas Sensing Properties of the Zinc Oxide Nanowhisker-derived Gas Sensor

  • Moon, Hyung-Sin;Kim, Sung-Eun;Choi, Woo-Chang
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.2
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    • pp.106-109
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    • 2012
  • A low power methane gas sensor with microheater was fabricated by silicon bulk micromachining technology. In order to heat up the sensing layer to operating temperature, a platinum (Pt) micro heater was embedded in the gas sensor. The line width and gap of the microheater was 20 ${\mu}m$ and 4.5 ${\mu}m$, respectively. Zinc oxide (ZnO) nanowhisker arrays were grown on a sensor from a ZnO seed layer using a hydrothermal method. A 200 ml aqueous solution of 0.1 mol zinc nitrate hexahydrate, 0.1 mol hexamethylenetetramine, and 0.02 mol polyethylenimine was used for growing ZnO nanowhiskers. Temperature distribution of the sensor was analyzed by infrared thermal camera. The optimum temperature for highest sensitivity was found to be $250^{\circ}C$ although relatively high (64%) sensitivity was obtained even at as low a temperature as $150^{\circ}C$. The power consumption was 72 mW at $250^{\circ}C$, and only 25 mW at $150^{\circ}C$.

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.

Preparation of Nano-Sized ZnO Powder by Utrasonic Spray Combustion Synthesis (초음파 분무연소 합성법에 의한 나노크기 ZnO 분말의 제조)

  • 이상원;천승호;공현식;전병세
    • Proceedings of the Materials Research Society of Korea Conference
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    • pp.126-126
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    • 2003
  • 산화아연은 높은 열전도도와 열용량을 갖으며, 결정 부피의 44%만이 아연 및 산소 이온으로 채워져 있어 결함의 생성이 다양하여 여러 가지 전기적, 광전기적, 촉매 특성등을 부여할 수 있어 산업전반에 널리 이용되고 있다. 따라서, 본 연구에서는 초음파 분무 연소합성법을 이용하여 Zinc nitrate hexahydrate를 산화제로, Carbohydrazide를 환원제로 사용하여, 연소합성을 위한 에너지를 최대희 얻기 위해 산화수와 환원수의 비율이 1:1이 되게 조절하여 전구체의 산화ㆍ환원 반응을 이용하여 액적의 체류시간, 농도, 온도, filtering 효과등을 조절하면서 액적 단위로 연소반응을 유도함으로써 부가적인 하소과정이 필요없이 상전이가 완료된 구형의 나노크기 ZnO 분말을 in-situ로 제조하여 입자의 크기와 형 태, 결정상등을 분석하였다.

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Photocatalytic Degradation of 3-Nitrophenol with ZnO Nanoparticles under UV Irradiation

  • Li, Jiulong;Ko, Weon Bae
    • Elastomers and Composites
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    • v.52 no.2
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    • pp.131-135
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    • 2017
  • Zinc nitrate hexahydrate [$Zn(NO_3){\cdot}6H_2O$] and sodium hydroxide [NaOH] were used as source reagents in the preparation of ZnO nanoparticles in an aqueous solution containing deionized water and ethanol in a ratio of 2:5 (v/v). ZnO nanoparticles were heated in an electric furnace at $700^{\circ}C$ for 2 h under an atmosphere of inert argon gas. The morphological and structural properties of the nanoparticles were characterized by scanning electron microscopy (SEM) and powder X-ray diffractometry (XRD). UV-vis spectrophotometry was used to analyze the photocatalytic degradation of 3-nitrophenol with ZnO nanoparticles as photocatalyst under ultraviolet irradiation at 254 nm. Evaluation of the kinetic of the photo-catalytic degradation of 3-nitrophenol indicated that the degradation of 3-nitrophenol with ZnO nanoparticles obeyed the pseudo-first order reaction rate model.