• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.11
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• pp.690-693
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• 2015

In this paper, in order to develop excellent Pb-free composition ceramics for ultrasonic sensor. The $SnO_2$-doped ($Na_{0.525}K_{0.443}Li_{0.037})(Nb_{0.883}Sb_{0.08}Ta_{0.037})O_3$)(abbreviated as NKL-NST) ceramics have been synthesized using the ordinary solid state reaction method. The effect of $SnO_2$-doping on their dielectric and piezoelectric properties was investigated. The ceramics doped with 0 wt% $SnO_2$ have the optimum values of piezoelectric constant($d_{33}$), piezoelectric figure of merit($d_{33}.g_{33}$), planar piezoelectric coupling coefficient($k_p$) and density : $d_{33}=195[pC/N]$, $d_{33}.g_{33}=5.62pm^2/N.kp=0.40$, $density=4.436[g/cm^3]$. suitable for duplex ultrasonic sensor application.

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.304-308
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• 2000

WO$_3$/SnO$_2$ceramics has been suggested as an effective sensing material for monitoring offensive odor or pollutant gases. This work was focussed on improving long-term stability, which has been a principal problem generally taking place in SnO$_2$semiconductor gas sensor. Miniaturized thick film gas sensors were fabricated by screen printing technique. Two types of sensor materials, W doped SnO$_2$and WO$_3$mixed SnO$_2$, were comparatively investigated on those long-term stability and sensitivites to several gases. Small amount of W doping(0.1 mol%) into SnO$_2$largely improved the long-term stability. The W(0.1 mol%) doped SnO$_2$gas sensor had higher sensitivities to both acetone and alcohol compared with WO$_3$(5 wt%) mixed SnO$_2$gas sensor. On the contrary, WO$_3$(5 wt%) mixed SnO$_2$gas sensor showed more superior sensitivity to cigarette smoke due to larger W content.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.8
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• pp.641-646
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• 2011

Ga-doped ZnO-$SnO_2$ (ZSGO) films were deposited by rf magnetron sputtering and their structural and electrical properties were investigated. In order to fabricate the target for sputtering, the mixture of ZnO, $SnO_2$ (1:1 weight ratio) and $Ga_2O_3$ (3.0 wt%) powder was calcined at $800^{\circ}C$ for 1 h. The substrate temperature was varied from room temperature to $300^{\circ}C$. The crystallographic properties and the surface morphologies of the films were studied by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The optical transmittances of the films were measured and the optical energy band gaps were obtained from the absorption coefficients. The resistivity variation with substrate temperature was measured. Auger electron spectroscopy was employed to find the atomic ratio of Zn, Sn, Ga and O in the film deposited at room temperature. ZSGO films exhibited the optical transmittance in the visible region of more than 80% and resistivity higher than $10\;{\Omega}cm$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.5
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• pp.254-259
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• 2003

In the fabrication process of transparent conducting thin films of the ATO (antimony-doped tin oxide) on a soda lime glass substrate by a sol-gel dip coating method, the effects of the $SiO_2$ buffer layer formed on the substrate and $N_2$ annealing treatment were investigated by XPS (X-ray photoelectron spectroscopy) analysis. Optical transmittance and electrical resistivity of the 400 nm-thick ATO thin films which were deposited on $SiO_2$ buffer layer/soda lime glass and then annealed under nitrogen atmosphere were 84 % and $5.0\times 10^{-3}\Omega \textrm{cm}$ respectively. The XPS analysis confirmed that a $SiO_2$ buffer layer inhibited Na ion diffusion from the substrate, resulting in prohibiting the formation of a secondary phase such as $Na_2SnO_3$ and SnO and increasing Sb ion concentration and ratio of $Sb^{5+}/Sb^{3+}$ in the film. And it was also found that $N_2$ annealing treatment leads to the reduction of $Sn^{4+}$as well as $Sb^{5+}$ however the reduction of $Sn^{4+}$ is more effective and therefore consequently results in decrease in the electrical resistivity to produce an excellent electrical properties of the film.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.476-482
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• 1997

A portable electronic nose system has been fabricated and characterized using an oxide semiconductor gas sensor array and pattern recognition techniques such as principal component analysis and back-propagation artificial neural network. The sensor array consists of six thick-film gas sensors whose sensing layers are Pd-doped $WO_{3}$, Pt-doped $SnO_{2}$, $TiO_{2}-Sb_{2}O_{5}-Pd$-doped $SnO_{2}$, $TiO_{2}-Sb_{2}O_{5}-Pd$-doped $SnO_{2}$ + Pd coated layer, $Al_{2}O_{3}$-doped ZnO and $PdCl_{2}$-doped $SnO_{2}$. The portable electronic nose system consists of an 16bit Intel 80c196kc as CPU, an EPROM for storing system main program, an EEPROM for containing optimized connection weights of artificial neural network, an LCD for displaying gas concentrations. As an application the system has been used to identify 26 carbon monoxide/hydrocarbon (CO/HC) car exhausting gases in the concentration range of CO 0%/HC 0 ppm to CO 7.6%/HC 400 ppm and the identification has been successfully demonstrated.

• Journal of information and communication convergence engineering
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• v.4 no.1
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• pp.18-22
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• 2006

A small-sized gas identification system has been fabricated and characterized using an integrated gas sensor array and artificial neural-network. The sensor array consists of four thick-film oxide semiconductor gas sensors whose sensing layers are $In_{2}O_{3}-Sb_{2}O_{5}-Pd-doped\;SnO_2$ + Pd-coated layer, $La_{2}O_{5}-PdCl_{2}-doped\;SnO_2,\;WO_{3}-doped\;SnO_{2}$ + Pt-coated layer and $ThO_{2}-V_{2}O_{5}-PdCl_{2}\;doped\;SnO_{2}$. The small-sized gas identification instrument is composed of a GMS 81504 containing an internal ROM (4k bytes), a RAM (128 bytes) and four-channel AD converter as MPU, LEDs for displaying alarm conditions for three gases (liquefied petroleum gas: LPG, liquefied natural gas: LNG and carbon monoxide: CO) and interface circuits for them. The instrument has been used to identify alarm conditions for three gases among the real circumstances and the identification has been successfully demonstrated.

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.143-143
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• 2005

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.428-438
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• 1994

In order to investigate the effect of $SnO_2$ on the growth of 123 phase in Y-Ba-Cu-0 system, O.1Sn-doped 123+Sn compact was coupled with Sn-free 123 compact by placing the former on the latter. In case of the coupled samples which were held at $1100^{\circ}C$ for 24hr and then at $970^{\circ}C$ for lhr, 123 phase grew from the surface of O.1Sn-doped 123+Sn compact toward the inner of Sn-free 123 compact. In case of the coupled samples which were held at $1100^{\circ}C$ for 48hr and then at $970^{\circ}C$ for lhr, it was not the 123 phase but Ba-Y-Sn grains that were observed. Ba-Y-Sn grains with a shape of bar was composed of Ba : Y : Sn=5 : 3 : 2, approximately.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1073-1077
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• 2003

The Sn $O_2$-based gas sensors can detect inflammable and toxic gases of low concentration by the modulation of surface resistance, but they lack in selectivity on the whole. To give selectivity to the Sn $O_2$-based gas sensors, studies on the sensing mechanism, selective gas sensing materials and signal processing techniques are demanded. Ethanol (C$_2$ $H_{5}$OH) and acetonitrile ($CH_3$CN) were confirmed to undergo catalytic oxidation on Sn $O_2$ by gas chromatography. PdCl$_2$-doped Sn $O_2$ showed excellent sensitivity to ethanol and acetonitrile, while La$_2$ $O_3$-doped Sn $O_2$ showed excellent sensitivity to ethanol, but poor sensitivity to acetonitrile. Using these two sensors and pattern recognition, the selectivity to acetonitrile is greatly enhanced. The minimum detection level of acetonitrile was 15 ppm in air and 20 to 100 ppm when exposed to interfering gases together with acetonitrile.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.79-79
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• 2009

Samples of Ta-doped in $In_2O_3-ZnO-SnO_2$(IZTO) with a doping level up to 4wt% were sintered at $1600^{\circ}C$ in $O_2$. The crystal phase of the samples was identified by an X-ray diffraction experiment. apparent density and porosity with sintered temperature from $1500^{\circ}C$ to $1640^{\circ}C$ are mesured by archimedes method. For each sample, the specific resistivity was determined. samples of sintered at $1600^{\circ}C$ had the highest density and lowest porousity and The Ta 0.25-wt%-doped IZTO ceramics had the lowest resistivity.