• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.294-299
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• 2000

For practical application as a humidity sensor SnO$_2$thick films devices were fabricated on the refresh type electrode by screen printing method and their material and humidity sensing properties were investigated. As a function of Sb$_{2}$/O$_{3}$ addition rate grain size was increased while porosity and initial resistance were rapidly decreased. And the area of resistance variation according to relative humidity was decreased with increasing heat treatment temperature. SnO$_2$thick film device heat treated at 95$0^{\circ}C$ and contained 0.05mole% Sb$_{2}$/O$_{3}$ had a best humidity sensing properties. From this result it is conformed that humidity sensing properties of SnO$_2$thick film devices could be approved by very small amount of Sb$_{2}$/O$_{3}$ addition.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.169-170
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• 2008

In this study, low temperature sintering property of the $0.6TiTe_3O_8-0.4MgTiO_3$ ceramics with sintering adds were investigated for LTCC application which enable to cofiring with Ag electrode. $TiTe_3O_8$ mixed with $MgTiO_3$ to improve the temperature property. In the X-ray diffraction patterns, the columbite structure of $TiTe_3O_8$ phase and ilmenite structure of $MgTiO_3$ phase were coexisted in all specimens. In the case of SnO addition, the bulk density and dielectric constant were increased but quality factor was decreased with amount of SnO additions. The TCRF of the $0.6TiTe_3O_8-0.4MgTiO_3$+xwt%SnO ceramics were shifted to negative direction. The dielectric constant, quality factor and TCRF of the $0.6TiTe_3O_8-0.4MgTiO_3$ ceramics with 2.5wt% addition of SnO sintered at $830^{\circ}C$ for 1hr were 29.86, 35,800 GHz, -0.58 ppm/$^{\circ}C$, respectively.

• Journal of the Korean Ceramic Society
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• v.46 no.3
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• pp.271-274
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• 2009

Redox investigation of Sn and S ion was attempted in alkaline earth borosilicate glass melts with only 1 mol% $Na_2O$ by means of Square Wave Voltammetry (SWV). According to voltammograms, there was only one peak due to $Sn^{4+}/Sn^{2+}$ in melt doped with $SnO_2$. The calculated standard enthalpy and entropy of the reduction of $Sn^{4+}$ to $Sn^{2+}$ were 116kJ/mole and 62 J/mol K, respectively. The determined redox ratio, [$Sn^{2+}$] / [$Sn^{4+}$] in the temperature range of $1300{\sim}1600^{\circ}C$ was in $0.4{\sim}2.1$. On the contrary, in the voltammogram of melt doped with $BaSO_4$ there was no peak due to $S^{4+}/S^o$ but shoulder that might be attributed to the adsorption of sulfur at the electrode. The absence of the peak related with $S^{4+}/S^o$ was discussed from the view-point of the thermal decomposition behavior of $BaSO_4$ in the glass batch.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.358-361
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• 2012

Co and Ni as catalysts in $SnO_2$ sensors to improve the sensitivity for $CH_4$ gas and $CH_3CH_2CH_3$ gas were coated by a solution reduction method. $SnO_2$ thick films were prepared by a screen-printing method onto $Al_2O_3$ substrates with an electrode. The sensing characteristics were investigated by measuring the electrical resistance of each sensor in a chamber. The structural properties of $SnO_2$ with a rutile structure investigated by XRD showed a (110) dominant $SnO_2$ peak. The particle size of the $SnO_2$:Ni powders with Ni at 6 wt% was about 0.1 ${\mu}m$. The $SnO_2$ particles were found to contain many pores according to a SEM analysis. The sensitivity of $SnO_2$-based sensors was measured for 5 ppm of $CH_4$ gas and $CH_3CH_2CH_3$ gas at room temperature by comparing the resistance in air to that in the target gases. The results showed that the best sensitivity of $SnO_2$:Ni and $SnO_2$:Co sensors for $CH_4$ gas and $CH_3CH_2CH_3$ gas at room temperature was observed in $SnO_2$:Ni sensors coated with 6 wt% Ni. The $SnO_2$:Ni gas sensors showed good selectivity to $CH_4$ gas. The response time and recovery time of the $SnO_2$:Ni gas sensors for the $CH_4$ and $CH_3CH_2CH_3$ gases were 20 seconds and 9 seconds, respectively.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.62-67
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• 2007

This paper presents a novel MEMS condenser microphone with rigid backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and backplate chips which are bonded together by gold-tin (Au/Sn) eutectic solder bonding. The membrane chip has 2.5 mm${\times}$2.5 mm, $0.5{\mu}m$ thick low stress silicon nitride membrane, 2 mm${\times}$2 mm Au/Ni/Cr membrane electrode, and $3{\mu}m$ thick Au/Sn layer. The backplate chip has 2 mm${\times}$2 mm, $150{\mu}m$ thick single crystal silicon rigid backplate, 1.8 mm${\times}$1.8 mm backplate electrode, and air gap, which is fabricated by bulk micromachining and silicon deep reactive ion etching. Slots and $50-60{\mu}m$ radius circular acoustic holes to reduce air damping are also formed in the backplate chip. The fabricated microphone sensitivity is $39.8{\mu}V/Pa$ (-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 1 dB between 20 Hz and 5 kHz.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.12 s.117
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• pp.1272-1278
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• 2006

This paper presents a novel MEMS condenser microphone with rigid backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and backplate chips which are bonded together by gold-tin(Au/Sn) eutectic solder bonding. The membrane chip has $2.5mm{\times}2.5mm$, 0.5${\mu}m$ thick low stress silicon nitride membrane, $2mm{\times}2mm$ Au/Ni/Cr membrane electrode, and 3${\mu}m$ thick Au/Sn layer. The backplate chip has $2mm{\times}2mm$, 150${\mu}m$ thick single crystal silicon rigid backplate, $1.8mm{\times}1.8mm$ backplate electrode, and air gap, which is fabricated by bulk micromachining and silicon deep reactive ion etching. Slots and $50{\sim}60{\mu}m$ radius circular acoustic holes to reduce air damping are also formed in the backplate chip. The fabricated microphone sensitivity is 39.8 ${\mu}V/Pa$(-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 1 dB between 20 Hz and 5 kHz.

• Clean Technology
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• v.9 no.3
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• pp.133-144
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• 2003

In this study, Insoluble catalyst electrode for oxide systems were manufactured, by using of them, carried out experiments on electrolytic treatment of dyeing wastewater containing persistent organic compounds, and then made a comparative study of the efficiency of treatment for environmental pollutants and whether each of them is valuable of not as an electrode for soluble electrode(Fe, Al) and insoluble electrode(SUS, R.C.E; Replaced Catalyst Electrode) which were used in the electrolytic system. Besides, it was investigated the conditions for electrolytic treatment to find the maximum efficiency of electrolytic treatment. As the result of this study, by using of insoluble catalyst electrode for oxide can solved the stability of electrode that is one of the greatest problems in order to put to practical use of electrolysis process in the treatment of the sewage and wastewater and the result runs as follows; 1. The durability of insoluble catalyst electrode(R.C.E) can be verified the most favorable when the molar ratio of $RuO_2-SnO_2-IrO_2-TiO_2$(4 compounds system) is 70/20/5/5. 2. The efficiency of treatment was obtained a more than 90% goodness for CODMn and also a good results for T-N removal in the experimental conditions of the distance of electrode 5 mm, time of electrolysis 60 minutes, permissible voltage 10V, processing capacity $0.5{\ell}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.5
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• pp.297-302
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• 2014

$La_{0.5}Sr_{0.5}CoO_3$ (LSCO) electrode thin films with a resistivity of ~ 1,600 ${\mu}{\Omega}cm$ were grown on c-$Al_2O_3$ (0001) substrate. $ZnSnO_3$ (ZTO) thin films with different thicknesses were directly grown on LSCO/c-$Al_2O_3$ (0001) substrates at a substrate temperature that ranged from 550 to $750^{\circ}C$ using Pulsed Laser Deposition (PLD). The secondary phase $Zn_2SnO_4$ occurred during the growth of ZTO films and it became more significant with further increasing substrate temperature. Polarization-electric-field (P-E) hysteresis characteristics, with a remnant polarization and coercive field of 0.05 ${\mu}C/cm^2$ and 48 kV/cm, respectively, were obtained in the ZTO film grown at $700^{\circ}C$ in 200 mTorr.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.3
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• pp.54-61
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• 2003

$SnO_2$ gas sensor for the detection DMMP, simulant of nerve gas was fabricated and its characteristics were examined. Sensing materials were $SnO_2$ added by TEX>$\alpha$-$Al_{2}O_{3}$ with 0∼20wt.% and $In_{2}O_{3}$ with 0∼3wt.% and were physically mixed each material. They were deposited by screen printing method on alumina substrate. The sensor was consisted of sensing electrode with interdigit(IDT) type in front and a heater in back side. Its dimension was 7$\times$10$\times$0.6$\textrm{mm}^2$. Crystallite size 8t phase identification, specific surface area and morphology of fabricated $SnO_2$ powders were analyzed by X-ray diffraction(XRD), surface area analyzer(BET) and by a scanning electron microscope(SEM), respectively. Sensor was measured as flow type and sensor resistance change was monitored as real time using LabVIEW program. The best sensitivities were 75% at adding 4wt.% TEX>$\alpha$-$Al_{2}O_{3}$, operating temperature $300^{\circ}C$ and 87% at adding 2wt.% $In_{2}O_{3}$, operating temperature $350^{\circ}C$ to DMMP 0.5ppm. Response and recovery times were about 1 and 3 min., respectively. Repetition measurement was very good with $\pm$3% in full scale. As a result, operating temperature was lower TEX>$\alpha$-$Al_{2}O_{3}$ than $In_{2}O_{3}$, but sensitivity was higher $In_{2}O_{3}$ than $\alpha$-$Al_{2}O_{3}$.

• 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.