• 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.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.1
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• pp.1-5
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• 2003

Zn$_4$SnSe$_{6}$ and Zn$_4$SnSe$_{6}$ :Co$^{2+}$ single crystals were by the chemical transport reaction method. They crystallized in the monoclinic structure. The direct energy band gaps of the Zn$_4$SnSe$_{6}$ and Zn$_4$SnSe$_{6}$ :Co$^{2+}$single crystals at 289k were found to be 2.146eV and 2.042eV. Optical absorption due to impurity in the Zn$_4$SnSe$_{6}$ :Co$^{2+}$single crystal was observed and described as originating from the electron transition between energy levels of Co$^{2+}$ion sited at T$_{d}$ symmetry point.y point.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.2
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• pp.68-73
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• 2003

$Zn_4SnSe_6$ and $Zn_4SnSe_6:Co^{2+}$ single crystals were grown by the chemical transport reaction(CTR) method. They were crystallized in the monoclinic structure. These temperature dependence of the optical energy gap were closely investigated over the temperature range 10[K]~300[K]. The direct energy gaps of $Zn_4SnSe_6$ and $Zn_4SnSe_6$:$Co^{2+}$ single crystals were given by 2.146[eV] and 2.042[eV] at 300[K]. The temperature dependence of the optical energy gap is well presented by the Varshni equation.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.414-417
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• 2011

Indium tin oxide (In:$SnO_2$) nanoparticles were synthesized employing a sol-gel combustion method followed by annealing. The TG, XRD, XPS and SEM results of the precursor powders and calcinated In:$SnO_2$ nanoparticles were investigated. Crystal structures were examined by powder XRD, and those results show shaper intensity peak at $25.6^{\circ}$ ($2{\theta}$) of $SnO_2$ by increased annealing temperature. A particle morphology and size was examined by SEM, and the size of the nanoparticles was found to be in the range of 20~30nm. In:$SnO_2$ films could controlled by nanoparticle material at various annealing temperature. The sol-gel combustion method was offered simple and effective route for the synthesis of In:$SnO_2$ nanoparticles.

• Journal of Sensor Science and Technology
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• v.20 no.5
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• pp.294-299
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• 2011

$SnO_2$ nanoparticles were synthesized by a hydrothermal method and gas sensors were fabricated using nanoparticles to detect dimethyl methylphosphonate(DMMP) gas. The prepared $SnO_2$ nanoparticles exhibited a high response(72 at $500^{\circ}C$) to 5 ppm DMMP gas compared to commercial $SnO_2$ nanopowders, but their recovery was relatively poor. Various metals(Ni, Sb, Nb) were added to the $SnO_2$ nanoparticles to improve their recovery properties. The focus of this study was to investigate the effects of metal oxide additives on DMMP sensing behavior in $SnO_2$ nanoparticles.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.464-466
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• 2009

This study tried to examine the suitability of strip casting process such as PFC (Planar Flow Casting) method for soldering Au-Sn strip. The effect of heat treatment on the tensile behavior and mechanical properties of an Au-Sn strip was investigated through tensile test, micro hardness test, X-ray diffraction (XRD), SEM, and TEM observations. It was apparent that 20-mm width Au-Sn strip could be well produced by using planar flow casting process. Tensile results showed that tensile strength increased from 338.3MPa to 310MPa and plastic strain improved from 0% to 1.5% with heat treatment ($170^{\circ}C$/70 hrs.). The microstructure of Au-Sn strip mainly consisted of two phases; $Au_5Sn(\zeta)$ and AuSn($\sigma$). It was also found that inhomogeneous amorphous local structure continuously changed to the homogeneous two phases microstructure with heat treatment. The fractographical observation after tensile test indicated the cleavage fracture mode of as-casted Au-Sn strip. On the other hand, the heat treated Au-Sn strip showed that fracture propagated along interface between brittle AuSn and ductile $Au_5Sn$ phases. The deformation behavior of strip casted Au-Sn alloy with microstructural evolution and the improve method for ductility of this alloy was also suggested.

• 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 the Korean Ceramic Society
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• v.33 no.8
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• pp.877-882
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• 1996

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.313-313
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• 2012

ZnO and $SnO_2$, well-known wide direct band-gap semiconductors, have been considered as the most promising functional materials due to their highly sensitive gas sensing and excellent optical properties. ZnO/$SnO_2$ epitaxial hetrostructure exhibited unique luminescence properties in contrast with individual tetra-pod ZnO and $SnO_2$ nanostructures. Polycrystalline $SnO_2$-based samples $Zn_xSn_{1-x}O_2$(x=0, 0.01, 0.03, 0.05) were prepared by solid state reaction and eco-friendly hydrothermal techniques. Scanning electron microscopy equipped with electron dispersive x-ray spectra confirms the formation of near stoichiometric $Zn_xSn_{1-x}O_2$ nanorods of diameter ~10 nm. X-ray diffraction analysis revealed the rutile structure, except for x=0.07, which may have a small part of $Zn_2SnO_4$ as a secondary phase.

• Journal of Electrochemical Science and Technology
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• v.10 no.3
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• pp.329-334
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• 2019

Sn-Cu alloy powders were prepared via a simple chemical reduction method for the negative electrode materials in lithiumion batteries. The addition of Cu can suppress the growth of Sn particles during synthetic process. Furthermore, the Cu also acts as a matrix phase against the volume change during cycling. With increasing amount of the Cu, a stable $Cu_6Sn_5$ phase formed in the Sn-Cu alloy and its cycle performance greatly enhanced depending on the Cu content. To promote the generation of the $Cu_6Sn_5$ phase, the synthesis temperature is raised to $60-100^{\circ}C$ from the ambient temperature. The Sn-Cu alloy powders prepared at elevated temperatures showed remarkable cycle performances. The Sn-Cu alloy powder obtained at $60^{\circ}C$ exhibited a significantly high volumetric capacity of over 2,000 mAh/cc at the 50th cycle.