• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
• /
• pp.939-939
• /
• 2006

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.253-253
• /
• 2012

Low temperature SiOx film process has being required for both silicon and oxide (IGZO) based low temperature thin film transistor (TFT) for application of flexible display. In recent decades, from low density and high pressure such as capacitively coupled plasma (CCP) type plasma enhanced chemical vapor deposition (PECVD) to the high density plasma and low pressure such as inductively coupled plasma (ICP) and electron cyclotron resonance (ECR) have been used to researching to obtain high quality silicon oxide (SiOx) thin film at low temperature. However, these plasma deposition devices have limitation of controllability of process condition because process parameters of plasma deposition such as RF power, working pressure and gas ratio influence each other on plasma conditions which non-leanly influence depositing thin film. In compared to these plasma deposition devices, neutral beam assisted chemical vapor deposition (NBaCVD) has advantage of independence of control parameters. The energy of neutral beam (NB) can be controlled independently of other process conditions. In this manner, we obtained NB dependent high crystallized intrinsic and doped silicon thin film at low temperature in our another papers. We examine the properties of the low temperature processed silicon oxide thin films which are fabricated by the NBaCVD. NBaCVD deposition system consists of the internal inductively coupled plasma (ICP) antenna and the reflector. Internal ICP antenna generates high density plasma and reflector generates NB by auger recombination of ions at the surface of metal reflector. During deposition of silicon oxide thin film by using the NBaCVD process with a tungsten reflector, the energetic Neutral Beam (NB) that controlled by the reflector bias believed to help surface reaction. Electrical and structural properties of the silicon oxide are changed by the reflector bias, effectively. We measured the breakdown field and structure property of the Si oxide thin film by analysis of I-V, C-V and FTIR measurement.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 하계학술대회 논문집 C
• /
• pp.1220-1222
• /
• 1995

In the design of a complementary electrochromic windows based on $WO_3/Li^+$ conducting electrolyte/$V_2O_5$ system, a characterization of electrochromic properties of $WO_3/V_2O_5$ complementary devices as a function of thickness combinations is necessary in order to predict such as the safe operating voltage, the optical modulation range and the optical switching response. In this paper, the effects of $WO_3\;and\;V_2O_5$ thin films thickness combinations on device performance were systematically investigated.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1994년도 추계학술대회 논문집
• /
• pp.179-182
• /
• 1994

We have investigated the optical and electrochromic properties of molybdenum oxide(MoO$_3$) films by thermal evaporation. The MoO$_3$films deposited at substrate temperatures below 200$^{\circ}C$ are found to be amorphous and annealed films at temperature 300$^{\circ}C$ for 1 hour in air are crystalline. The optical energy gap calculated from the transmittance and reflectance spectra of MoO$_3$ films is near 2.75 eV and 3.25 eV for amorphous films and crystalline films, respectively. The MoO$_3$ thin films exhibit light blue to dark blue optical modulation on lithium intercalation and have a uniform transmittance modulation over a wavelength range of 300∼1100 nmcompared to tungsten oxide films.

• 한국표면공학회지
• /
• 제43권1호
• /
• pp.31-35
• /
• 2010

Coatings of Ni-17 at.%W were electroplated on a steel substrate, and their corrosion behavior was investigated between 600 and $800^{\circ}C$ in an Ar-0.2%$SO_2$ atmosphere. They delayed the corrosion of the steel substrate. They were corroded into an outer NiO-rich layer, and an inner ($WO_3+NiO+NiWO_4$)-mixed oxide layer. Below these oxide layers, a sulfide layer gradually formed.

• 한국분말재료학회지
• /
• 제11권2호
• /
• pp.111-117
• /
• 2004

The oxidation behavior of 91 WC-9Co hardmetal in weight percentage has been studied in the present work as a part of the development of recycling process. The morphological and compositional changes of the WC-Co hardmetal with oxidation time at 90$0^{\circ}C$ were analyzed by using surface observation and X-ray diffraction. respective]y. As the oxidation time increased, the WC-Co hardmetal was continuously expanded to form porous oxide mixtures of $CoWO_4$ and $WO_3$. The morphology of porous oxide mixture was basically dependent on initial shape of the WC-Co hardmetal. From thermo-gravimetric (TG) analysis, it was found that the oxidation rate was increased with increasing oxidation temperature and oxygen content in the flowing atmospheric gas. The fraction of oxidation versus time curves showed S-curve relationship at a given of oxidation temperature. These oxidation behaviors of the WC-Co hardmetal were discussed in terms of previously proposed kinetic models.

• Journal of Industrial and Engineering Chemistry
• /
• 제67권
• /
• pp.437-447
• /
• 2018

Visible-light-driven wide bandgap semiconductor photocatalysts were commonly developed via doping or coupling with another narrow bandgap metal oxide. However, these approaches required extra processing. The aim of study was to evaluate the photocatalytic performance of narrow bandgap $WO_x$ nanoparticles. A mixture of $WO_2$ and $WO_3$ nanoparticles were synthesized using solution precipitation technique. The photodegradation of RhB by these nanoparticles more effective in UV light than in visible light. In antibacterial susceptibility assay, $WO_x$ nanoparticles demonstrated good antibacterial against Gram-positive bacteria. The cell wall of bacterial was the main determinant in antibacterial effect other than $W^{4+}/W^{6+}$ ions and ROS.

• 대한화학회지
• /
• 제39권3호
• /
• pp.157-162
• /
• 1995

비화학량론적 산화물$WO_{3-x}$의 비화학량 x값과 전기전도도를 350~700$^{\circ}C$의 온도 범위와 $2{\times}10_{-1}\;to\;1{\times}10_{-5}$ atm의 산소분압 범위에서 측정하였다. 비화학량론적 조성식에서 x의 생성엔탈피 ${\Delta}H^{\circ}_f$가 양의 값을 가지는 것으로 보아 결함생성은 흡열 과정이고, 결함생성의 산소분압 의존성인 1/n값은 -1/5.7~-1/6.1로 변하였다. 전기전도도의 활성화에너지는 각 산소분압에 따라 0.24~0.29 eV이었고, 전기전도도의 산소분압 의존성인 1/n은 -1/4.3~-1/7.6의 값을 나타내었다. 이로부터 n형 반도체로써 산화텅스텐의 결함모델은 낮은 온도에서는 1가로 하전된 산소공위가 우세하지만 온도가 상승함에 따라 2가로 하전된 산소공위가 우세해진다.

• Bulletin of the Korean Chemical Society
• /
• 제35권3호
• /
• pp.913-918
• /
• 2014

Five mol % tungsten-doped tin oxide ($W_{0.05}Sn_{0.95}O_2$, TTO5) was prepared by co-precipitation of $SnCl_4{\cdot}5H_2O$ and $WCl_4$, followed by calcination at $1000^{\circ}C$. The as-prepared TTO5 was in the pure cassiterite phase with a particle size of ~50 nm and optical bandgap of 2.51 eV. Herein it was applied for the formation of TTO5/$TiO_2$ heterojunctions by covering the TTO5 surface with $TiO_2$ by sol-gel method. Under visible-light irradiation (${\lambda}{\geq}420$ nm), TTO5/$TiO_2$ showed a significantly high photocatalytic activity in removing gaseous 2-propanol (IP) and evolving $CO_2$. It is deduced that its high visible-light activity is caused by inter-semiconductor holetransfer between the valence band (VB) of TTO5 and $TiO_2$, since the TTO5 nanoparticle (NP) exhibits the absorption edge at ~450 nm and its VB level is located more positive side than that of $TiO_2$. The evidence for the hole-transport mechanism between TTO5 and $TiO_2$ was also investigated by monitoring the holescavenging reaction with 1,4-terephthalic acid (TA).

• 한국재료학회지
• /
• 제13권10호
• /
• pp.691-696
• /
• 2003

To improve the photocatalyticactivity of $TiO_2$-coated coal fly ash, tungsten hydroxide was doped by impregnation method and was oxidized by heat treatment in temperature ranges of $WO^{\circ}C$ for 2 hrs. The changes of crystal structure and crystal size of $TiO_2$and $WO_3$on coal fly ash were investigated by X-ray diffraction analysis. The crystal structure of titanium dioxide showed only anatase type and $TiO_2$-$WO_3$ compounds appeared in the heat treatment temperature ranges of $500∼600^{\circ}C$. By adding $V_3$in $TiO_2$coated on fly ash, the growth of crystal size of anatase was restrained and the anatase phase was stabilized in temperature ranges of TEX>$500∼<800^{\circ}C$. And $WO_3$acted as a trap site of electrons excited from anatase by irradiating UV. The maximum removal efficiency of NO gas for $TiO_2$/$WO_3$-coated coal fly ash was 84% and appeared when the ammonium tungstate of $1.3${\times}$10^{-3}$ M was doped and then heated at $600^{\circ}C$ for 2 hrs.