• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.9-12
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• 2004

The effect of x wt% CuO-y wt% $V_2O_5$ content on the microwave properties of $(Pb_{0.45}Ca_{0.55})[(Fe_{0.5}Nb_{0.5})_{0.9}Sn_{0.1}]O_3$ (PCFNS) ceramics was investigated. In order to decrease the sintering temperature and use as a Low Temperature co-firing Ceramics (LTCC), CuO-$V_2O_5$ are added in the PCFNS. The bulk density, dielectric constant (${\varepsilon}_r$) and quality factor(Q${\cdot}f_0$) increased with increase in CuO content within a limited value. The microwave properties were degraded with increases in $V_2O_5$ content. The temperature coefficient of the resonant frequency (${\tau}_f$) of PCFNS was shifted to positive value abruptly with increasing the $V_2O_5$ content, while the ${\tau}_f$ was slightly shifted to positive value with increasing the CuO content. The optimized microwave properties, ${\varepsilon}_r$ = 88, Q${\cdot}f_0$ = 6100 (GHz), and ${\tau}_f$ = 18 ppm/$^{\circ}C$, were obtained in $(Pb_{0.45}Ca_{0.55})[(Fe_{0.5}Nb_{0.5})_{0.9}Sn_{0.1}]O_3$ with 0.2wt% CuO 0.05 wt% $V_2O_5$ and sintered at $1000^{\circ}C$ for 3 h. The relationship between the microstructure and microwave dielectric properties of ceramics was studied by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM)

• Journal of the Korean Electrochemical Society
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• v.8 no.3
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• pp.139-145
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• 2005

[ $SnO_x$ ] films on the flexible substrate of PET film were prepared at ambient temperature under a $(CH_3)_4Sn(TMT: tetra-methyl tin)-H_2-O_2$ atmosphere in order to obtain transparent conductive polymer by using ECR-MOCVD(Electro Cyclotron Resonance Metal Organic Chemical Yfpor Deposition) system. The prepared $SnO_x$ thin films show generally over $90\%$ of optical transmittance at wavelength range of 380-780nm and about $1\times10^{-2\~3}ohm{\cdot}cm$ of electrical resistivity. In the present study, effects of $O_2/TMT\;and\;H_2/TMT$ mole ratio on the properties of $SnO_x$ films are investigated and the other process parameters such as microwave power, magnetic current power, substrate distance and working pressure are fixed. Based on our experimental results, the $SnO_x$ film composition ratio of Sn and O directly influences on the electrical and optical properties of the films prepared. The $SnO_x$ film with low electric resistivity and high transmittance could be obtained by controlling the process parameters such as $O_2/TMT\;and\;H_2/TMT$ mole ratio, which play an important role to change the composition ratio between Sn and O. An increase of $O_2/TMT$ mole ratio brought on the increases 0 content in the $SnO_x$ film. On the other hand, an increase of $H_2/TMT$ mole ratio lead to decreases the oxygen content in the film. The optimized composition ratio of oxygen : tin Is determined as 2.4: 1 at $O_2/TMT$ of 80 and $H_2/TMT$ of 40 mole ratio, respectively.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.85-91
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• 2005

$SnO_2$ films were prepared at room temperature under a $(CH_3)_4Sn-H_2-O_2$ atmosphere in order to obtain transparent conductive polymer by using ECR-MOCVD (Electron Cyclotron resonance -Metal Organic Chemical Vapor Deposition) system. The electrical properties of the films were investigated as function of process parameters such as deposition time, microwave power, magnetic current power, magnet/showering/substrate distance and working pressure. An increase in microwave power and magnetic current power brought on $SnO_2$ film formation with low electric resistivity. On the other hand, the effects of process parameters described above on optical properties were insignificant in the range of our experimental scope. The transmittance and reflectance of the films prepared by the ECR-MOCVD exhibited their average values of 93-98% at wave length range of 380-780 nm and 0.1-0.5%, respectively. The grain size of the $SnO_2$ films that are also insensitive with the process parameters were in the range of 20-50 nm. On the basis of experimental data obtained in the present study, electrical resistivity of $7.5{\times}10^{-3}ohm{\cdot}cm$, transmittance of 93%, and reflectance of 0.2% can be taken as optimum values.

• Journal of Sensor Science and Technology
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• v.24 no.6
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• pp.364-367
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• 2015

Tin oxide thin films were fabricated on glass substrates by the successive ionic layer adsorption and reaction (SILAR) method at room temperature and ambient pressure. Before measuring their properties, all samples were annealed at $500^{\circ}C$ for 2 h in air. Film thickness increased with the number of cycles; X-ray diffraction patterns for the annealed $SnO_2$ thin films indicated a $SnO_2$ single phase. Thickness of the $SnO_2$ films increased from 12 to 50 nm as the number of cycles increased from 20 to 60. Although the optical transmittance decreased with thickness, 50 nm $SnO_2$ thin films exhibited a high value of more than 85%. Regarding electronic properties, sheet resistance of the films decreased as thickness increased; however, the measured resistivity of the thin film was nearly constant with thickness ($3{\times}10^{-4}ohm/cm$). From Hall measurements, the 50 nm thickness $SnO_2$ thin film had the highest mobility of the samples ($8.6cm^2/(V{\cdot}s)$). In conclusion, optical and electronic properties of $SnO_2$ thin films could be controlled by adjusting the number of SILAR cycles.

• Korean Journal of Materials Research
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• v.3 no.4
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• pp.319-326
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• 1993

The effects of $SnO_2$ crystallite size on the powder characteristics, the resistance in air and the sensitivity to 0.5 vol % $H_2$, CO-air mixture were observed. The size of SnO, powder was controlled by calcining temperature variation ($500^{\circ}C$ ~$1100^{\circ}C$) of $\alpha$-stannic acid fabricated from $SnCl_4 \cdot xH_2O$. Its crystallite size. evaluated from TEM image, was in the range of 8-54nm. With the reduction of crystallite size, the adsoption peak of $H_2O$ on FTIR curve became more clear while the lattice parameters were invariable. As the crystallite size decreased, with elements of thick film, the temperatures showing a minimum resistance in air and a maximum sensitivity to H, gas reduced. The temperature variations were assigned to the changes of activation energy of the active adsorbates, and it was suggested that the decrease of activation energy can be one of the reasons for the' sensitivity increase with the' fine powder.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.145-145
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• 2010

In this paper, we report that the effects of hydrogen doping on the electrical and optical properties of typical transparent conducting oxide films such as ZnO and $SnO_2$ prepared by magnetron sputtering. Recently, density functional theory (DFT) calculations have shown strong evidence that hydrogen acts as a source of n-type conductivity in ZnO. In this work, the beneficial effect of hydrogen incorporation on Ga-doped ZnO thin films was demonstrated. It was found that hydrogen doping results a noticeable improvement of the conductivity mainly due to the increases in carrier concentration. Extent of the improvement was found to be quite dependent on the deposition temperature. A low resistivity of $4.0{\times}10^{-4}\;{\Omega}{\cdot}cm$ was obtained for the film grown at $160^{\circ}C$ with $H_2$ 10% in sputtering gas. However, the beneficial effect of hydrogen doping was not observed for the films deposited at $270^{\circ}C$. Variations of the electrical transport properties upon vacuum annealing showed that the difference is attributed to the thermal stability of interstitial hydrogen atoms in the films. Theoretical calculations also suggested that hydrogen forms a shallow-donor state in $SnO_2$, even though no experimental determination has yet been performed. We prepared undoped $SnO_2$ thin films by RF magnetron sputtering under various hydrogen contents in sputtering ambient and then exposed them to H-plasma. Our results clearly showed that the hydrogen incorporation in $SnO_2$ leads to the increase in carrier concentration. Our experimental observation supports the fact that hydrogen acting as a shallow donor seems to be a general feature of the TCOs.

• Microbiology and Biotechnology Letters
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• v.22 no.2
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• pp.175-181
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• 1994

A bacterial strain producing highly viscous polysaccharide(A29 POL) was isolated from soil and identified sa Bacillus sp. A29. The cultural conditions of the Bacillus sp. A29 for the polysaccharide prouction were dextrin 12%, soytone 0.2%, SnCl$_{2}$ $\cdot $2H$_{2}$O 0.02%, Na$_{2}$HPO$_{4}$ $\CDOT $12H$_{2}$O 0.36%, L-alanine 0.01%, initial pH6.8, and 30$\circ $C at pH 3 FOR 4 days. Final viscosity of the culture broth was 65, 000 cp and then the amount of produced polysaccharide was 8.3 g/l. A29 POL was composed of glucose and xylose. A29 POL showed high viscosity at low concentration(0.1%) and in the presence of the salts such as NaCl or CaCl$_{2}$. A29 POL showed high viscosity acid condition and at alkali condition and high pseudoplasticity in the presence of a NaCl or CaCl$_{2}$. It was shown that the viscosity at high temperature(80$\circ $C) was decreased but it was recovered at low temperature (20$\circ $C. A29 POL was able to from film and gel in the presence of MgSO$_{4}$ $\CDOT $7H$_{2}$O, Na$_{2}$CO$_{3}$ \CDOT $H$_{2}$O, MnSO$_{4}$ $\CDOT $ 7H$_{2}$O. A29 POL had anionic charge.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.3
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• pp.95-100
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• 2016

In this work, tin oxides were obtained by the liquid reduction precipitation method and hydrothermal process using $SnCl_2{\cdot}2H_2O$, $N_2H_4$, and NaOH. Tin oxide crystals having different sizes and morphologies could be achieved. The powders were characterized by X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FE-SEM). Depending on the molar ratio of the raw materials, tin oxide crystalline with the spherical and rectangular plate-like shape could be obtained, the crystal phase was SnO and $Sn_6O_4(OH)_4$. And the obtained SnO crystals by a hydrothermal reaction showed various shapes, such as, spherical, plate-like and flower-like architectures depending on the temperature conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.218-218
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• 2012

Nanocrystalline $SnO_2$ colloids are synthesized by hydrolysis of $SnCl_4{\cdot}5H_2O$ in aqueous ammonia solution. The synthesized $SnO_2$ nanoparticles with ca. 15 nm in diameter are coated on a fluorinedoped thin oxide (FTO) conductive substrate and heated at $550^{\circ}C$. The annealed $SnO_2$ film is treated with aqueous $TiCl_4$ solution, which is sensitzied with MK-2 dye (2-cyano-3-[5'''-(9-ethyl- 9H-carbazol-3-yl)-3',3'',3''',4-tetra-n-hexyl-[2,2',5',2'',5'',2''']-quater thiophen-5-yl]). Compared to bare $SnO_2$ film, the conversion efficiency is significantly improved from 0.22% to 3.13% after surface treatment of $SnO_2$ with $TiCl_4$, which is mainly due to the large increases in both photocurrent density from 1.33 to $9.46mA/cm^2$ and voltage from 315 to 634 mV. It is noted that little change in the amount of the adsorbed dye is detected from 1.21 for the bare $SnO_2$ to $1.28{\mu}mol/cm^2$ for the $TiCl_{4-}$ treated $SnO_2$. This indicates that the photocurrent density increased by more than 6 times is not closely related to the dye loading concentration. From the photocurrent and voltage transient spectroscopic studies, electron life time increases by about 13 order of magnitude, whereas electron diffusion coefficient decreases by about 3.6 times after $TiCl_4$ treatment. Slow electron diffusion rate offers sufficient time for regeneration kinetics. As a result, charge collection efficiency of about 40% before $TiCl_4$ treatment is improved to 95% after $TiCl_4$ treatment. The large increase in voltage is due to the significant increase in electron life time, associated with upward shift of fermi energy.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.68.2-68.2
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• 2017

인체접촉시 니켈도금의 알러지 반응을 억제하기 위한 대체 도금기술인 비 시안계 Cu-Sn 합금도금을 개발함에 있어서, 황산구리5수화물과 황산제일주석을 금속염으로 하여 황산 및 계면활성제, 유화제 등을 포함한 각종 유기첨가제를 포함하였고 특히 은백색조의 외관 색상과 안정적인 Cu-Sn 합금전착을 위해 2종의 착화제인 EDTP (Ethylenediaminetetrapropanol, $C_{14}H_{32}N_2O_4$)와 TEA (Triethanolamine)를 첨가한 비 시안계 Cu-Sn 합금 도금액을 도출하였다. Cu-Sn 합금도금 피막 조성의 균일화를 도모하기 위해서는 합금 도금액중의 Cu와 Sn 금속이온 농도를 일정하게 유지하는 것이 필요하다. 그러나 합금 도금액 중 2가 주석이온($Sn^{2+}$)은 수용액 중에서 4가 주석이온($Sn^{4+}$)으로 산화됨으로써 도금액 색상이 백탁이 되고 Stannic Hydroxide($Sn(OH)_4$, $SnO_2{\cdot}2H_2O$)이 생성되어 대량의 침전물이 침강하는 문제점이 발생되는 등시간 경과에 따른 도금액의 경시 변화가 발생되었다. 상기 침전물은 연속여과에 의해 제거 가능하나 합금 도금액 중 $Sn^{2+}$ 농도가 지속적으로 감소하게 된다. 이는 합금 도금액 중 금속이온 비율이 변동함으로써 합금도금 피막의 조성비를 일정하게 유지하는 것이 곤란해진다. 이에 $Sn^{4+}$ 침전물 생성을 방지하기 위한 산화방지제를 개발하고 또한 산화방지제의 첨가에 따른 도금 피막 외관에 미치는 영향을 평가하여 외관 개선을 위한 광택제를 개발하고자 한다. 본 연구의 결과를 토대로 니켈도금과 동등 이상의 기능 특성을 갖는 비 시안계 Cu-Sn 합금도금액을 개발하여 실용화하는 것을 목적으로 하였다.