• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.407-410
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• 2012

The properties of Al-doped ZnO (AZO) films were investigated as a function of H2/(Ar + H2) gas ratio using an AZO (2 wt% Al2O3) ceramic target in a radio frequency (RF) magnetron sputtering system. The deposition process was done at 200 ℃ and in 2 × 10-2Torr working pressure and with various ratios of H2/(Ar + H2) gas. During the AZO film deposition process, partial H2 gas affected the AZO film characteristics. The electron resistivity (~ 9.21 × 10-4 Ωcm) was lowest and mobility (~17.8 ㎠/Vs) was highest in AZO films when the H2/(Ar + H2) gas ratio was 2.5%. When the H2/(Ar + H2) gas ratio was increased above 2.5%, the electron resistivity increased and mobility decreased with increasing H2/(Ar + H2) gas ratio in AZO films. The carrier concentration increased with increasing H2/(Ar + H2) gas ratio from 0% to 7.5%. This phenomenon was explained by reaction of hydrogen and oxygen and additional formation of oxygen vacancy. The average optical transmission in the visible light wavelength region over 90% and an orientation of the deposition was [002] orientation for AZO films grown with all H2/(Ar + H2) gas ratios.

• 한국결정성장학회지
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• 제22권3호
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• pp.122-126
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• 2012

$Al_2O_3$ 2 wt%가 도핑 된 ZnO(AZO) 타겟으로RF 스퍼터링 장비를 사용하여 $H_2/(Ar+H_2)$ 가스 비율에 따른 AZO 박막을 증착 후, 이들 박막의 특성을 조사하였다. AZO 박막은 $200^{\circ}C$, $2{\times}10^{-2}$ 공정조건에서 $H_2/(Ar+H_2)$ 가스 비율을 변화시키면서 증착하였다. AZO박막증착 중 수소가스의 첨가는 박막의 특성에 영향을 미쳤다. $H_2/(Ar+H_2)$ 가스 비율이 2.5 %일 때 비 저항(${\sim}9.21{\times}10^{-4}\;{\Omega}cm$)과 전자 이동도(${\sim}17.8\;cm^2/Vs$)는 각각 최소값과 최대값을 나타내었다. $H_2/(Ar+H_2)$ 가스 비율이 2.5 % 이상일 때는 $H_2/(Ar+H_2)$ 가스 비율이 증가할수록 비저항은 점차로 증가하였고 전자 이동도는 점차적으로 감소하였다. 전자 운반자 농도는 $H_2/(Ar+H_2)$ 가스 비율이 증가함에 따라 0 %에서 7.5 %까지 점차로 증가하였다. $H_2/(Ar+H_2)$ 가스 비율에 따라 증착된 박막의 가시광선 파장 범위에서 평균 광 투과도는 90 % 이상이었고 성장방향은 [002]이었다.

• Korean Chemical Engineering Research
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• 제47권6호
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• pp.710-714
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• 2009

본 연구에서는 석탄가스의 환원도와 석탄가스에 함유된 $H_2O/H_2S$ 농도변화에 따른 세 가지 종류의 아연계 탈황제의 반응성능을 회분식 유동층반응기에서 분석하였다. 가스화에서 생성되는 가스의 조성은 환원도가 각각 다른 KRW(Kellogg-Rust-Westinghouse) 공기이용 가스 조성, Shell 산소이용 가스 조성, 고등기술연구원의 가스 조성을 기준으로 모사가스를 이용하여 입구의 $H_2O$와 $H_2S$ 농도를 변화시켜 실험을 수행하였다. $H_2O$의 농도는 5부터 30%까지 $H_2S$의 농도는 0.5에서 2%로 변화시켜 탈황성능을 분석하였다. 실험 결과 $H_2O$의 농도가 증가할수록 탈황성능이 감소하고 입구의 $H_2S$ 농도가 증가할수록 탈황반응기 후단의 $H_2S$ 농도 역시 증가하였다. 모든 조건에서 환원도에 따른 탈황성능 변화는 없었으며 탈황성능은 최저 99.5%로 건식탈황제를 이용하여 99% 이상의 $H_2S$ 제거 성능을 보이는 것을 확인하였다.

• 한국가스학회지
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• 제7권3호
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• pp.7-12
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• 2003

[ $CO_2$ ]와 $H_2S$ 각각 1.37, 1.70 몰$\%$를 포함하고 있는 산성의 천연가스를 sweetening하고자한다. 본 연구에서는 천연가스 하부에서 100 MMSCFD 안에 산 가스의 농도가 5 ppm이 되도록 amine 처리능력을 디자인하는 것이다. 천연가스에 포함된 $CO_2,\;H_2S,\;H_2O$와 amino 성분들의 K-값은 Kent-Eisenberg model를 사용하였다. Ball과 Veldman이 새롭게 디자인한 gas sweetening 공정을 상응 정상상태 모사기를 이용하여 모델링한 후 최적화하였다. 모사 결과는 현재 운전하고 있는 공정보다 더 많은 경제적인 개선을 이끌 것이다.

• 센서학회지
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• 제31권5호
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• pp.348-352
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• 2022

Hydrogen gas (H₂) which is odorless, colorless is attracting attention as a renewable energy source in varions applications but its leakage can lead to disastrous disasters, such as inflammable, explosive, and narcotic disasters at high concentrations. Therefore, it is necessary to develop H₂ gas sensor with high performance. In this paper, we confirmed that H₂ gas detection ability of SnO₂ based H₂ gas sensor along with thermal treatment effect of SnO₂. Proposed SnO₂ based H₂ gas sensor is fabricated by MEMS technologies such as photolithgraphy, sputtering and lift-off process, etc. Deposited SnO₂ thin films are thermally treated in various thermal treatement temperature in range of 500-900 ℃ and their H₂ gas detection ability is estimatied by measuring output current of H₂ gas sensor. Based on experimental results, fabricated H₂ gas sensor with SnO₂ thin film which is thermally treated at 700 ℃ has a superior H₂ gas detection ability, and it can be expected to utilize at the practical applications.

• 센서학회지
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• 제21권3호
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• pp.167-171
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• 2012

Ag- and Pd-loaded $SnO_2$ nanowire network sensors were prepared by the growth of $SnO_2$ nanowires via thermal evaporation, the coating of slurry containing $SnO_2$ nanowires, and dropping of a droplet containing Ag or Pd nanoparticles, and subsequent heat treatment. All the pristine, Pd-loaded and Ag-loaded $SnO_2$ nanowire networks showed the selective detection of $C_2H_5OH$ with low cross-responses to CO, $H_2$, $C_3H_8$, and $NH_3$. However, the relative gas responses and gas selectivity depended closely on the catalyst loading. The loading of Pd enhanced the responses($R_a/R_g$: $R_a$: resistance in air, $R_g$: resistance in gas) to CO and $H_2$ significantly, while it slightly deteriorated the response to $C_2H_5OH$. In contrast, a 3.1-fold enhancement was observed in the response to 100 ppm $C_2H_5OH$ by loading of Ag onto $SnO_2$ nanowire networks. The role of Ag catalysts in the highly sensitive and selective detection of $C_2H_5OH$ is discussed.

• 자원리싸이클링
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• 제12권5호
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• pp.42-49
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• 2003

넓은 입도분포를 가지는 헤마타이트 철광석을 사용하여 $H_2$ 및 $H_2$-CO 혼합가스 분위기에서 환원 및 탄회특성에 대하여 고찰하였다. 환원에 의한 활성화에너지 값은 약 20kJ/mol 였다. 환원 및 탄화단계에서 무게변화는 환원단계에서는 약 28% 감소하였고, 탄화단계에서는 약 5%증가하였다. 이는 이론 계산식에 의한 값과 거의 일치하였다. 온도, 입도 및 가스비($_H2$/CO=1～5 범위)에 따른 탄화속도는 온도가 낮을수록 입자가 작을수록 그리고 가스비가 작을수록 탄화속도가 증가하였다. 또한 $H_2$의 가스비($H_2$/CO=1)가 낮을 때는 유리카본(C, free carbon)이 발생하였다. 수소가스를 혼합하였을 경우가 탄화속도는 증가하였으나, 수소분율에 비례하여 증가하지는 않았다. 혼합가스 중 수소분율($X_{H2}$ )이 0.5일 때 ($H_2$/CO=1) 탄화속도가 최대였다. 이때 수소가 탄화철 생성과정에 있어서 촉매역할을 한 것으로 추정된다.

• Applied Science and Convergence Technology
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• 제23권6호
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• pp.392-397
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• 2014

CuO nanotubes are synthesized using $TeO_2$ nanorod templates for application to $H_2S$ gas sensors. $TeO_2$ nanorod templates were synthesized by using the VS method through thermal evaporation. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction showed that the synthesized nanotubes were monoclinic-structured polycrystalline CuO with diameter and wall thickness of approximately 100~300 nm and 5~10 nm, respectively. The CuO nanotube sensor showed responses of 136~325% for the $H_2S$ concentration of 0.1~5 ppm at room temperature. These response values are approximately twice as high as that of the CuO nanowire sensor for the same concentrations of $H_2S$ gas. Along with the investigation of the performance of the sensors, the mechanisms of $H_2S$ gas sensing of the CuO nanotubes are also discussed in this study.

• 한국재료학회지
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• 제18권11호
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• pp.628-633
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• 2008

ZnO nanopowders were synthesized by the sol-gel method using hydrazine reduction, and their gas responses to 6 gases (200 ppm of $C_2H_5OH$, $CH_3COCH_3$, $H_2$, $C_3H_8$, 100 ppm of CO, and 5 ppm of $NO_2$) were measured at $300\;{\sim}\;400^{\circ}C$. The prepared ZnO nanopowders showed high gas responses to $C_2H_5OH$ and $CH_3COCH_3$ at $400^{\circ}C$. The sensing materials prepared at the compositions of [$ZnCl_2$]:[$N_2H_4$]:[NaOH] = 1:1:1 and 1:2:2 showed particularly high gas responses ($S\;=\;R_a/R_g,\;R_a$ : resistance in air, $R_g$ : resistance in gas) to 200 ppm of $C_2H_5OH$($S\;=\;102.8{\sim}160.7$) and 200 ppm of $CH_3COCH_3$($S\;= 72.6{\sim}166.2$), while they showed low gas responses to $H_2$, $C_3H_8$, CO, and $NO_2$. The reason for high sensitivity to these 2 gases was discussed in relation to the reaction mechanism, oxidation state, surface area, and particle morphology of the sensing materials.

• 한국세라믹학회지
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• 제37권1호
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• pp.1-5
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• 2000

Cathodoluminescence(CL) properties of ZnO:Zn green phosphor were investigated. ZnO:Zn phosphor was synthesized by varying reducing agents and firing temperatures. ZnS, charcoal and 5% H2 gas mixed with 95% N2 gas(5H2-95N2) were used as the reducing agent and atmosphere. The highest CL intensity of ZnO:Zn phosphor was observed under the condition of 5H2-95N2 atmosphere and firing temperature of 90$0^{\circ}C$ for 1h. Charocal and ZnO as reducing agents in the syntehsis of ZnO:Zn phosphor exhibited about 60% and 40%, respectively, of the CL intensity obtained with 5H2-95N2 atmosphere.