• 제목/요약/키워드: SnO2 gas sensor

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Gas Sensing Characteristics and Preparation of SnO2 Nano Powders (SnO2 나노 분말의 합성 및 가스 감응 특성)

  • Lee, Ji-Young;Yu, Yoon-Sic;Yu, Il
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.7
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    • pp.589-593
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    • 2011
  • [ $SnO_2$ ]nano powders were prepared by solution reduction method using tin chloride($SnCl_2{\cdot}2H_2O$), hydrazine($N_2H_4$) and NaOH. The $SnO_2$ thick films for gas sensors were fabricated by screen printing method on alumina substrates and annealed at $300^{\circ}C$ in air, respectively. XRD patterns of the $SnO_2$ nano powders showed the tetragonal structure with (110) dominant orientation. The particle size of $SnO_2$ nano powders at the ratio of $SnCl_2:N_2H_4$+NaOH= 1:6 was about 60 nm. The sensing characteristics were investigated by measuring the electrical resistance of each sensor in a test box. Sensitivity of $SnO_2$ gas sensor to 5 ppm $CH_4$gas and 5 ppm $CH_3CH_2CH_3$ gas was investigated for various $SnCl_2:N_2H_4$+NaOH proportion. The highest sensitivity to $CH_4$ gas and $CH_3CH_2CH_3$ gas of $SnO_2$ sensors was observed at the $SnCl_2:N_2H_4$+NaOH= 1:8 and $SnCl_2:N_2H_4$+NaOH= 1:6, respectively. Response and recovery times of $SnO_2$ gas sensors prepared by $SnCl_2:N_2H_4$+NaOH= 1:6 was about 40 s and 30 s, respectively.

A Study on the Gas Sensing Characteristics of Pt/$SnO_2$ Gas Sensor (Pt/$SnO_2$ 가스 센서의 가스 감지 특성에 관한 연구)

  • Lee, J.H.;Kim, C.K.;Kim, J.G.;Kim, D.J.
    • Proceedings of the KIEE Conference
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    • 1997.07d
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    • pp.1304-1307
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    • 1997
  • A hydrogen gas sensor utilizing Pt/$SnO_2$ system was fabricated by the pressed pellet method. The crystal structure, direction of the crystal, crystal size and microstructure between the catalyst and the support ($SnO_2$) were characterized with Electron Diffraction Analysis, Transmission Electron Microscopy, Scanning Electron Microscopy. After the reactor with a Pt/$SnO_2$ sample was run with a flow rate of 30sccm (a mixture of $0.5%H_2$ in $N_2$) for a while, the resistance of $SnO_2$ was saturated, but the $SnO_2$ kept absorbing $H_2$ gas. $H_2$ gas sensing properties of Pt/$SnO_2$ were investigated at several temperatures. As a result, it was observed that Pt/$SnO_2$ has high sensitivity at $300^{\circ}C$ and $400^{\circ}C$.

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Gas Sensing Characteristics of WO3-Doped SnO2 Thin Films Prepared by Solution Deposition Method (용액적하법으로 제조된 WO3 첨가 SnO2 박막의 가스감응 특성)

  • Choi, Joong-Ki;Cho, Pyeong-Seok;Lee, Jong-Heun
    • Korean Journal of Materials Research
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    • v.18 no.4
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    • pp.193-198
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    • 2008
  • $WO_3$-doped $SnO_2$ thin films were prepared in a solution-deposition method and their gas-sensing characteristics were investigated. The doping of $WO_3$ to $SnO_2$ increased the response ($R_a/R_g,\;R_a$: resistance in air, $R_g$: resistance in gas) to $H_2$ substantially. Moreover, the $R_a/R_g$ value of 10 ppm CO increased to 5.65, whereas that of $NO_2$ did not change by a significant amount. The enhanced response to $H_2$ and the selective detection of CO in the presence of $NO_2$ were explained in relation to the change in the surface reaction by the addition of $WO_3$. The $WO_3$-doped $SnO_2$ sensor can be used with the application of a $H_2$ sensor for vehicles that utilize fuel cells and as an air quality sensor to detect CO-containing exhaust gases emitted from gasoline engines.

Effect of Film Thickness on Gas Sensing Behavior of Thin-Film-Type Gas Sensor (박막 형 가스 센서에 있어서 가스 감지 속도에 대한 막 두께의 영향)

  • Yu, Do-Joon;Jun Tamaki;Norio Miura;Noboru Yamazoe;Park, Soon-Ja
    • Korean Journal of Materials Research
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    • v.6 no.7
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    • pp.716-722
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    • 1996
  • Effect of Film thickness on the sensing behavior of thin-film-type ags sensor has been analyzed by deriving an equation form a simple model, and the equation was applied to the sensing behavior of ${SnO}_{2}$ and CuO-${SnO}_{2}$ thin-film sensors. It was revealed, from the equation,that the gas sensing property was closely related to gas diffusivity into the film which was a function of film thickness, reactivity of the gas detected with sensing material, operating temperature, etc. The equation derived was well consistent with the experimental results from ${SnO}_{2}$ and CuO-${SnO}_{2}$ thin-film sensors and explained their different ${H}_{2}S$ sensing behaviors. Finally, a medel was suggested, explainning the effect of gas diffusivity on sensing be havior of oxide semiconductor sensor.

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Characterization of ZnO Nanorods and SnO2-CuO Thin Film for CO Gas Sensing

  • Lim, Jae-Hwan;Ryu, Jee-Youl;Moon, Hyung-Sin;Kim, Sung-Eun;Choi, Woo-Chang
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.6
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    • pp.305-309
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    • 2012
  • In this study, ZnO nanorods and $SnO_2$-CuO heterogeneous oxide were grown on membrane-type gas sensor platforms and the sensing characteristics for carbon monoxide (CO) were studied. Diaphragm-type gas sensor platforms with built-in Pt micro-heaters were made using a conventional bulk micromachining method. ZnO nanorods were grown from ZnO seed layers using the hydrothermal method, and the average diameter and length of the nanorods were adjusted by changing the concentration of the precursor. Thereafter, $SnO_2$-CuO heterogeneous oxide thin films were grown from evaporated Sn and Cu thin films. The average diameters of the ZnO nanorods obtained by changing the concentration of the precursor were between 30 and 200 nm and the ZnO nanorods showed a sensitivity value of 21% at a working temperature of $350^{\circ}C$ and a carbon monoxide concentration of 100 ppm. The $SnO_2$-CuO heterogeneous oxide thin films showed a sensitivity value of 18% at a working temperature of $200^{\circ}C$ and a carbon monoxide concentration of 100 ppm.

A study on the gas reaction mechanism in catalyst/$SnO_2$ gas sensor (촉매/$SnO_2$ 가스 센서의 반응 구조에 관한 연구)

  • 이재홍;김창교;김진걸;조남인;김덕준
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.7 no.2
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    • pp.276-283
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    • 1997
  • A dry impregnation method was used for preparing pellet type Pt/$SnO_2$ gas sensor. The crystal structure, direction of the crystal, crystal size and microstructure between the catalyst and the support ($SnO_2$) were characterized with electron diffraction analysis, transmission electron microscopy, scanning electron microscopy. The characterization indicates that when Pt/$SnO_2$ sample is calcined at $400^{\circ}C$, the Cl content associated with the Pt phase diminishes and the part of Pt is moved into $SnO_2$ support. This results in the enhancement of gas sensitivity. After the reactor with a Pt/$SnO_2$ sample was run with a flow rate of 30 sccm (a mixture of 0.5% $H_2$ in $_N2$) for a while, the resistance of $SnO_2$ was saturated, but the $SnO_2$ kept absorbing $H_2$ gas. This indicates that the surface state was saturated. For the 14 ppm $H_2$ gas, the sensitivity of Pt/$SnO_2$ devices was about 81% at an operating temperature of $300^{\circ}C$.

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Preparation of Pt-, Ni- and Cr-Decorated SnO2 Tubular Nanofibers and Their Gas Sensing Properties (Pt, Ni, Cr이 도포된 튜브형 SnO2 나노섬유의 합성과 가스 감응특성)

  • Kim, Bo-Young;Lee, Chul-Soon;Park, Joon-Shik;Lee, Jong-Heun
    • Journal of Sensor Science and Technology
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    • v.23 no.3
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    • pp.211-215
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    • 2014
  • The Pt-, Ni- and Cr-decorated tubular $SnO_2$ nanofibers for gas sensors were prepared by the electrospinning of polyvinylpyrrolidone (PVP) nanofibers containing Pt, Ni, and Cr precursors, the sputtering of $SnO_2$ on the electrospun PVP nanofibers, and the removal of sacrificial PVP parts by heat treatment at $600^{\circ}C$ for 2 h. Pt-decorated tubular $SnO_2$ nanofibers showed high response ($R_a/R_g=210.5$, $R_g$: resistance in gas, $R_a$: resistance in air) to 5 ppm $C_2H_5OH$ at $350^{\circ}C$ with negligible cross-responses to other interference gases (5 ppm trimethylamine, $NH_3$, HCHO, p-xylene, toluene and benzene). Cr-decorated tubular $SnO_2$nanofibers showed the selective detection of p-xylene at $400^{\circ}C$. In contrast, no significant selectivity to a specific gas was found in Ni-decorated tubular $SnO_2$ nanofibers. The selective and sensitive detection of gases using Pt-decorated and Cr-decorated tubular $SnO_2$ nanofibers were discussed in relation to the catalytic promotion of gas sensing reaction.

[ SnO2 ] Gas Sensors Using LTCC (Low Temperature Co-fired Ceramics) (LTCC 를 이용한 SnO2 가스 센서)

  • Cho, Pyeong-Seok;Kang, Chong-Yun;Kim, Sun-Jung;Kim, Jin-Sang;Yoon, Seok-Jin;Hieu, Nguyen Van;Lee, Jong-Heun
    • Korean Journal of Materials Research
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    • v.18 no.2
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    • pp.69-72
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    • 2008
  • A sensor element array for combinatorial solution deposition research was fabricated using LTCC (Low-temperature Co-fired Ceramics). The designed LTCC was co-fired at $800^{\circ}C$ for 1 hour after lamination at $70^{\circ}C$ under 3000 psi for 30 minutes. $SnO_2$ sol was prepared by a hydrothermal method at $200^{\circ}C$ for 3 hours. Tin chloride and ammonium carbonate were used as raw materials and the ammonia solution was added to a Teflon jar. 20 droplets of $SnO_2$ sol were deposited onto a LTCC sensor element and this was heat treated at $600^{\circ}C$ for 5 hours. The gas sensitivity ($S\;=\;R_a/R_g$) values of the $SnO_2$ sensor and 0.04 wt% Pd-added $SnO_2$ sensor were measured. The 0.04 wt% Pd-added $SnO_2$ sensor showed higher sensitivity (S = 8.1) compared to the $SnO_2$ sensor (S = 5.95) to 200 ppm $CH_3COCH_3$ at $400^{\circ}C$.

Detection of Blood Agent Gas Using $SnO_2$ Thin Film Gas Sensor

  • Choi, Nak-Jin;Kwak, Jun-Hyuk;Lim, Yeon-Tae;Joo, Byung-Su;Lee, Duk-Dong;Bahn, Tae-Hyun
    • Journal of Korean Society for Atmospheric Environment
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    • v.20 no.E2
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    • pp.69-75
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    • 2004
  • In this study, thin film gas sensor based on tin oxide was fabricated to examine its characteristics. Target gas is acetonitrile ($CH_3$CN) which is a blood simulant for the chemical warfare agent. Sensing materials are SnO$_2$ SnO$_2$/Pt, and Sn/Pt with thickness from 1000 to 3000 $\AA$. The sensor consists of a sensing electrode with inter-digit (IDT) type in front side and a heater in rear side. Resistance changes of sensing materials are monitored on real time basis using a data acquisition board with a 12-bit analog to digital converter. Sensitivities are measured at different operating temperatures also with different gas concentrations and film thickness. The high sensitivity is obtained for Sn (3000 $\AA$)/Pt (30 $\AA$) at 30$0^{\circ}C$ for 3 ppm. Response and recovery times were about 40 and 160 s, respectively. Repetition measurements showed very good results with $\pm$3% in full scale range.

Fast Responding Gas Sensors Using Sb-Doped SnO2 Nanowire Networks (Sb-첨가 SnO2 나노선 네트워크를 이용한 고속응답 가스센서)

  • Kwak, Chang-Hoon;Woo, Hyung-Sik;Lee, Jong-Heun
    • Journal of Sensor Science and Technology
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    • v.22 no.4
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    • pp.302-307
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    • 2013
  • The Sb-doped $SnO_2$ nanowire network sensors were prepared by thermal evaporation of the mixtures between tin and antimony powders. Pure $SnO_2$ nanowire networks showed high sensor resistance in air ($99M{\Omega}$), similar gas responses to 4 diffferent gases (5 ppm $C_2H_5OH$, CO, $H_2$, and trimethylamine), and very sluggish recovery speed (90% recovery time > 800 s). In contrast, 2 wt% Sb-doped $SnO_2$ showed the selective detection toward $C_2H_5OH$ and trimethylamine, relatively low resistance ($176k{\Omega}$) for facile measurement, and ultrafast recovery speed (90% recovery times: 6 - 18 s). The change of gas sensing charactersitics by Sb doping was discussed in relation to gas sensing mechanism.