• Korean Journal of Materials Research
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• v.16 no.8
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• pp.503-510
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• 2006

The measurement of specific gases is based on the reversible conductivity change of sensing materials in semiconductor type gas sensors. For an application as gas sensors of high sensitivity, porous $SnO_2$ films have been fabricated by anodizing of pure Sn foil in oxalic acid and characteristics of anodic tin oxide films have been investigated. Pore diameter and distribution were dependent on process conditions such as electrolyte concentration, applied voltage, anodizing temperature, and time. Characteristics of anodic films were explained with current density-time curves.

• Journal of the Korean institute of surface engineering
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• v.31 no.2
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• pp.109-116
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• 1998

Highly transparent conductive pure and fluorine-doped tin oxide(FT0, $SnO_2$ : F) films have been prepared by low pressure metal organic chemical vapor deposition (LP-MOCVD) from various mixtures of tetramethyitin(TMT) with oxygen or oxygen containing ozone. The properties of TO films have been changed with the variation of gases, flow rate, and substrate temperature. The nsing of oxygen containing ozone instead of pure oxygen, reduced substrate temperature by 100-$150^{\circ}C$ while maintaining same thickness. The films prepared by using ozone showed the resistivity in the range from $10^~2$ to $10^{~3}\Omega$cm, and the mobiiity from 10 to $14\textrm{cm}^2$/Vs. Fluorine-doped tin oxide films had properties such as the resistivity about $10^{-4}\Omega$cm, and the mobility from 14 to $19\textrm{cm}^2$/Vs.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.2
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• pp.135-154
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• 1992

This study was performed to analyze bond strength, the alterations of the interfaces between metal films which are populary used and considered to contribute to the chemical reaction with porcelain, according to constant ion- beam- mixing, and the relation between interfacial chemical reactions and bond strength in metal/porcelain specimens. For this study, three seperate metals : selected-gold, indium and tin were chosen ; each to be bonded to a seperate body porcelain. Bonding occurs when the metal is deposited to the body porcelain using a vacuum evaporator. The vacuum evaporator used $10^{-5}\sim10^{-6}$ Torr vacuum states for the evaporation of various metals (Au, Sn, In). Ion-beam-mixing of the porcelain/metal interfaces caused reactions when the Ar+ was implanted into thin films using a 80 KeV accelerator. These ion-beam-mixed specimens were then compared with an unmixed control group. An analysis of bond strength and ionic changes between the the metal and porcelain was performed by electron spectroscopy of chemical analysis (ESCA) and scratch test. The finding led to the following conclusions : 1. Light microscopic views of the scratch test : The ion-beam-mixed Au/porcelain specimen showed narrower scratched streams than the unmixed specimen. However, the Sn/porcelain, In/porcelain specimens showed no differences in the two conditions. 2. Acoustic emissions in scratch tests : The ion-mixed Au/porcelain, In/porcelain specimens showed signals closer to the metal/porcelain interfaces than unmixed specimens. Conversely, the ion-mixed Sn/porcelain specimen showed more critical signals in superficial portions than unmixed specimens. 3. After ion- beam-mixing, the Au/porcelain specimen showed apparently increased bond strength, and the In/porcelain specimen showed very slightly increased bond strength. However, the Sn/porcelain specimen showed no differences between ion mixed specimen and the unmixed one. 4. ESCA analysis : The ion-beam-mixed Au/porcelain specimen showed a higher peak separated value (4.3eV) than that of the unmixed specimen(3.65eV), the ion-beam-mixed In/porcelain specimen showed a higher peak separated value (9.43eV) than that of the unmixed specimen(7.6eV) and the ion-beam-mixed Sn/porcelain specimen showed a higher peak separated value (8.79eV) than that of the unmixed specimen(8.5eV). 5. Interfacial changes were observed in the ion-mixed Au/porcelain, In/porcelain and Sn/porcelain specimens. Especially, significant interfacial changes were measured in the ion- mixed Sn/porcelain specimen. Tin dioxide(SnO2) and a combination of pure tin and tin dioxide (Sn+SnO2) were produced. 6. In the Au/porcelain specimen, the interfacial chemical reaction showed increased bond strength between gold and porcelain substrate. But, in the In/porcelain, Sn/porcelain specimens, interfacial chemical reactions did not affected the bond strength between metal and porcelain substrate. Especially, bonding strength on the ion mixed Sn/porcelain specimen showed the least amount of difference.

• Korean Journal of Materials Research
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• v.11 no.1
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• pp.15-19
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• 2001

Transparent and conducting tin oxide thin films were prepared on soda lime silicate glass by thermal chemical vapour deposition. Thin films were fabricated from mixtures of tetramethyltin (TMT) as a precursor, oxygen or oxygen containing ozone as an oxidant. The properties of fabricated tin oxide films are highly changed with variations of substrate temperature. Optimized thin films could be prepared on TMT, which flow rate of 8 sccm, oxygen flow rate of 150 sccm and substrate temperature of 38$0^{\circ}C$. We reduced deposition temperature about$ 180^{\circ}C$ by using of oxygen containing ozone instead of pure oxygen and resistivity of thin films was decreased from ~ ${\times}10^{-2}{\Omega}cm$ to ~${\times}10^{-3}{\Omega}cm$.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.4
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• pp.25-31
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• 2012

In the synthesis of nanoparticles (NPs) via wet chemical reduction using tin(II) acetate precursor, the effects of green reducing agents (sugar) and a capping agent (gelatin) on the formation of NPs were analyzed as functions of synthesis conditions and time. When glucose was used as the reducing agent, it was observed that irregular chainlike shapes, aggregates of NPs, were formed during the synthesis at $70-110^{\circ}C$. The NPs were determined as $SnO_2$ from the fast Fourier transform (FFT) pattern. In the synthesis at $110^{\circ}C$ by using sucrose, fine spherical NPs of ~10 nm in diameter were formed after the synthesis time of 3 h. As the time increased to 9 h, the chainlike NP aggregates besides irregularly aggregated spherical NPs were also formed locally. However, the chainlike NP aggregates were only observed when the synthesis was conducted at $130^{\circ}C$. The spherical NPs and chainlike NP aggregates were analyzed to be pure Sn and $SnO_2$, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.2
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• pp.11-20
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• 2010

The effects of heat treatment on matte pure tin-plated Cu leadframes at high temperature and humidity conditions were investigated. After 1800 hrs of storage at $55^{\circ}C/85%$ RH, approximately 14.5 ${\mu}m$ long striation-shaped whiskers were observed on the surface of the without postbake treatment (WOPB) samples, while no whiskers were found in with postbake treatment (WPB) samples. The preferred orientations of Sn grains in WOPB and WPB sample did not change after the postbake treatment at $125^{\circ}C$ for 1 hr. However, both changed from (112) to (321) and (101), respectively, after 1800 hrs of storage at $55^{\circ}C/85%$ RH. The tensile stress of 8 MPa generated in as-plated sample was changed to a compression stress of 17 MPa after 2 days in room temperature storage. Due to the grain growth during postbake treatment, the WPB samples have more regular grains than the WOPB samples. In the as-plated sample, 0.32 ${\mu}m$ thickness of planar intermetallic compound (IMC) was observed. The IMCs in the WOPB and WPB samples had two distinct layers with large grains of $Cu_6Sn_5$ and with small grains of ${\eta}-Cu_{6.26}Sn_5$.

• Journal of the Korean Chemical Society
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• v.27 no.6
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• pp.424-482
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• 1983

Determination for $Ta_2O_5$,$Nb_2O_5$ and $SnO_2$ in tin slags was investigated by X-ray spectrometric method. Standard addition-dilution method was attempted and showed a comparable accuracy with standard calibration curve method. Pure chemicals($Ta_2O_5$,$Nb_2O_5$ and $SnO_2$) were added to the samples and diluted with silica or ferric oxide. For the determination of $Ta_2O_5$and$SnO_2$ , silica was more suitable than ferric oxide while the latter was more preferable than the former for $Nb_2O_5$.

• Journal of Conservation Science
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• v.10 no.1 s.13
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• pp.31-37
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• 2001

The metallurgical investigation of four lumps of bronze from the third building site of the northern workshop site at the Neungsan-ri temple site in Buyeo was performed. The microstructures of a section of sample was observed by SEM and qualitative and quantitative analysis of the sample was performed by EDS. The results are as follows: Sample 1 of the lump of bronze from northern workshop site in the third building site at Neungsan-ri temple site and sample 2 are speculated to be low-quality bronze resulting from refinery of matte which formed on the process of bronze refinery. Sample 3 is speculated as a lump of bronze which is one of Cu-Sn system and the one made by alloy only with pure bronze and tin on the process of bronze refinery. Sample 4 is confirmed as a lump of bronze which is one of Cu-Sn-Pb system from alloy of tin and lead into pure bronze. It is believed that the third building site at Neungsan-ri temple site in Buyeo produced bronze matte by refinery of copper ore or produced low-quality bronze by melting matte imported from outside.

• Advances in nano research
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• v.5 no.3
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• pp.203-214
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• 2017

In this study we present the reaction mechanism of $Cu_2ZnSnSe_4$ (CZTSe) nanoparticles synthesized by microwave-assisted chemical synthesis. We performed reactions every 10 minutes in order to identify different phases during quaternary CZTSe formation. The powder samples were analyzed by x-ray diffraction (XRD), Raman spectroscopy, energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results showed that in the first minutes copper phases are predominant, then copper and tin secondary phases react to form ternary phase. The quaternary phase is formed at 50 minutes while ternary and secondary phases are consumed. At 60 minutes pure quaternary CZTSe phase is present. After 60 minutes the quaternary phase decomposes in the previous ternary and secondary phases, which indicates that 60 minutes is ideal reaction time. The EDS analysis of pure quaternary nanocrystals (CZTSe) showed stoichiometric relations similar to the reported research in the literature, which falls in the range of Cu/(Zn+Sn): 0.8-1.0, Zn/Sn: 1.0-1.20. In conclusion, the evolution pathway of CZTSe synthesized by this novel method is similar to other synthesis methods reported before. Nanoparticles synthesized in this study present desirable properties in order to use them in solar cell and photoelectrochemical cell applications.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.611-616
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• 2010

A cobalt oxide - tin oxide nanocomposite based gas sensor on an $SiO_2$ substrate was fabricated. Granular thin film of tin oxide was formed by a rheotaxial growth and thermal oxidation method using dc magnetron sputtering of Sn. Nano particles of cobalt oxide were spin-coated on the tin oxide. The cobalt oxide nanoparticles were synthesized by polymer-assisted deposition method, which is a simple cost-effective versatile synthesis method for various metal oxides. The thickness of the film can be controlled over a wide range of thicknesses. The composite structures thus formed were characterized in terms of morphology and gas sensing properties for reduction gas of $H_2$. The composites showed a highest response of 240% at $250^{\circ}C$ upon exposure to 4% $H_2$. This response is higher than those observed in pure $SnO_2$ (90%) and $Co_3O_4$ (70%) thin films. The improved response with the composite structure may be related to the additional formation of electrically active defects at the interfaces. The composite sensor shows a very fast response and good reproducibility.