• Journal of the Semiconductor & Display Technology
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• v.4 no.1 s.10
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• pp.29-34
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• 2005

Tungsten oxide($WO_{3}$) is suitable to materials for photochromic window in the visible region. The resistivities of CdS, $WO_{3}$, and $WO_{3}$/CdS films prepared by thermal evaporation method were $4.61\times 10\^{3}$, $7.59\times10^{3}$, and $6.29\times10^{3}$ $\omega$ cm. And x-ray diffraction patterns of CdS, $WO_{3}$/CdS films showed a preferred orientation of hexagonal(002), and the monoclinic(020) structure, respectively. The optical transmission were measured that the cut-on wavelength were 510nm, 380nm for CdS and $WO_{3}$ films respectively, and the transmission spectrum of $WO_{3}$/CdS was shifted into the visible region. Photoluminescence(PL) spectra showed the two peaks at 2.8 eV and 3.2 eV for the as-grown sample($WO_{3}$/CdS ($500{\AA}$), but the other sample($WO_{3}$/CdS ($1000{\AA}$)) had a peak energy value of 2.8 eV. The photochromism of $WO_{3}$/CdS films showed that the excitation of electron-hole pairs and subsequent coloration is shifted into visible-light range. And the spectral behavior of coloration turned out to be proportional to the excited electron-hole pairs creation rate of CdS film. This result is interpreted in terms of charge carrier injection from the CdS-layer into the $WO_{3}$ films. We found a value of about 2.8 eV of $WO_{3}$/CdS film which is somewhat higher than peak energy of 2.54 eV using CBD prepared by Bechinger et. al.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.159-165
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• 2022

To enhance the photocatalytic activities of WO₃ photocatalysts, fluorine doping was performed to induce the oxygen vacancies. Both plasma and direct vaper fluorination were carried out for fluorine doping, and photocatalytic activities were examined by using methylene blue dye. Oxygen vacancies of the plasma and direct vaper fluorinated WO₃ photocatalysts were measured to be 14.65 and 18.59%, which increased to about 23 and 56% at pristine WO₃ photocatalysts. The degradation efficiency of methylene blue was also determined about 1.7 and 3.4 times higher than pristine WO₃ photocatalysts, respectively, depending on oxygen vacancies increased. In addition, it was confirmed that the bandgap process energy decreased from 2.95 eV to 2.64 and 2.45 eV after fluorine doping. From this result, it is considered that the direct vaper fluorination has an advantage for increasing the photocatalytic activities of WO₃ compared to that of the plasma fluorination.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.632-639
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• 2021

In this research, fluorine doping was performed to enhance the photocatalytic activities of WO₃ which were measured using methylene blue dye. WO_3-xF_x photocatalyts were prepared by a vaper phase fluorination during a sintering for preparing WO₃ photocatalysts from a WCl₆ precursor. The bandgap energy of WO₃ photocatalysts decreased from 2.95 eV to 2.54 eV, and the oxygen vacancies site increased by about 55% after fluorine doping. In addition, the initial degradation efficiency of methylene blue showed that the fluorine doped sample showed a 6-fold increase in photocatalytic activities from 10% to 60% compared to that of the untreated sample. It is believed that fluorine is doped to reduce the band gap of photocatalysts, enabling the catalytic activity with low energy, and that oxygen vacancies-generated surface defects increase the visible light absorption region of WO₃ photocatalysts, thereby increasing photocatalytic activity. In this study, it was confirmed that fluorine-doped WO_3-xF_x photocatalysts with an excellent photocatalytic activity can be manufactured easily using a one-step vaper phase fluorination that does not require a post-treatment process.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.601-604
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• 1998

NOX detecting gas sensors using TiO2 doped tungsten oxide semiconductor were prepared and their electrical and sensing characteristics have been investigated. In normal air condition, the sensors of WO3, TiO2 doped WO3 show grain boundary heights of 0.34 eV, 0.25 eV, respectively. The grain boundary barrier energy variation was increased by doping TiO2 into large variation of resistance to NOX gases. And doping the TiO2 4 wt.%, the particle size of WO3 polycrystal films showed higher sensitivity and better sorption characteristics to NOX gas than the pure WO3 films material in air at operating temperature of $350^{\circ}C.$ The TiO2 doped WO3 semiconductor gas sensor shows nano-sized particle size and good sensitivity to sub-ppm concentration of NOX.

• Korean Journal of Materials Research
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• v.21 no.2
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• pp.83-88
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• 2011

Nano-technology is a super microscopic technology to deal with structures of 100 nm or smaller. This technology also involves the developing of $TiO_2$ materials or $TiO_2$ devices within that size. The aim of the present paper is to synthesize $WO_x$ doped nano-$TiO_2$ by the Sonochemistry method and to evaluate the effect of different percentages (0.5-5 wt%) of tungsten oxide load on $TiO_2$ in methylene blue (MB) elimination. The samples were characterized using such different techniques as X-ray diffraction (XRD), TEM, SEM, and UV-VIS absorption spectra. The photo-catalytic activity of tungsten oxide doped $TiO_2$ was evaluated through the elimination of methylene blue using UV-irradiation (315-400nm). The best result was found with 5 wt% $WO_x$ doped $TiO_2$. It has been confirmed that $WO_x-TiO_2$ could be excited by visible light (E<3.2 eV) and that the recombination rate of electrons/holes in $WO_x-TiO_2$ declined due to the existence of $WO_x$ doped in $TiO_2$.

• Korean Journal of Materials Research
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• v.24 no.1
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• pp.6-12
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• 2014

In the present work, $WO_3$ and $WO_3-TiO_2$ were prepared by the chemical deposition method. Structural variations, surface state and elemental compositions were investigated for preparation of $WO_3-TiO_2$ sonocatalyst. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM) were employed for characterization of these new photocatalysts. A rhodamine B (Rh.B) solution under ultrasonic irradiation was used to determine the catalytic activity. Excellent catalytic degradation of an Rh.B solution was observed using the $WO_3-TiO_2$ composites under ultrasonic irradiation. Sonocatalytic degradation is a novel technology of treating wastewater. During the ultrasonic treatment of aqueous solutions sonoluminescence, cavitaties and "hot spot" occurred, leading to the dissociation of water molecules. In case of a $WO_3$ coupled system, a semiconductor coupled with two components has a beneficial role in improving charge separation and enhancing $TiO_2$ response to ultrasonic radiations. In case of the addition of $WO_3$ as new matter, the excited electrons from the $WO_3$ particles are quickly transferred to $TiO_2$ particle, as the conduction band of $WO_3$ is 0.74 eV which is -0.5 eV more than that of $TiO_2$. This transfer of charge should enhance the oxidation of the adsorbed organic substrate. The result shows that the photocatalytic performance of $TiO_2$ nanoparticles was improved by loading $WO_3$.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.26-30
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• 2011

In order to improve the energy conversion efficiency of dye-sensitized solar cell (DSSC), the photoelectrode was manufactured by using $TiO_2$ and $WO_3$ on combination effects of two conduction bands. The smash procedure of $TiO_2$ and $WO_3$ was carried out by using a paint shaker to enlarge the contact area of semiconductor with dye and electrolyte. The energy conversion efficiency of prepared DSSC was improved about two times from current-voltage curve based on effects of $WO_3$ and smash. The mechanism was suggested that the conduction band of $WO_3$ worked for prohibiting the trapping effects of electrons in conduction band of $TiO_2$. This result is attributed to the prevention of electron recombination between electron in conduction band of $TiO_2$ with dye and electrolyte. Impedance results indicate the improved electron transport at interface of $TiO_2$/dye/electrolyte.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1508-1510
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• 1999

스퍼터 퇴적 $WO_3$ 박막에 대해 열처리에 따른 전기적특성 및 구조적특성을 각각 4탐침법 및 AFM 관측에 의해 조사해 보고, 또한 스퍼터링시의 산소가스 유량비에 따른 $WO_3$ 박막의 막질을 ESCA에 의해 평가하였다 실험 결과 열처리에 의해 $WO_3$ 박막 표면의 평균거칠기가 $2.45\AA$에서 $152\AA$으로 크게 증가함을 알 수 있었다 또한 스퍼터시 산소유량비에 따른 효과를 ESCA로 관측한 결과, 열처리전에는 주피크가 34eV에서 나타남에 비해 열처리 후에는 36eV전후에서 나타났다.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.107-114
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• 2018

In this exploration, the nuclear magnetic resonance of the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ Single Crystals using FT-NMR spectrometer is investigated. The line width of the resonance line for the $^{207}Pb$ nucleus decreases as temperature increases due to motional narrowing. The chemical shift of $^{207}Pb$ NMR spectra also increases as temperature decreases for both crystals. The spinlattice relaxation times $T_1$ of $^{39}K$ nucleus were calculated as a function of temperature (180 K~400 K). The $T_1$ of $^{207}Pb$ nucleus decreases as temperature increases. The dominant relaxation mechanism at the studied temperature range can be deduced as the Raman process, which is the coupling between lattice vibrations and the nuclear spins. This deduction is substantiated by the fact that the nuclear spin-lattice relaxation rate $1/T_1$ of the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ single crystal is proportional to $T^2$, or temperature squared. The activation energies for the $^{207}Pb$ nucleus in $PbWO_4:Mn^{2+}$ and $PbWO_4:Dy^{3+}$ single crystals are $E_a=49{\pm}1meV$ and $E_a=47{\pm}2meV$, respectively.

• The Journal of Industrial Distribution & Business
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• v.11 no.8
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• pp.7-19
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• 2020

Purpose: Prior studies rarely investigated the effects of the Word of Mouse (WoM) information on consumers' motivation and willingness to purchase a product. Furthermore, few scholars have studied how word-of-mouth information works and they fail to find consistent results. Research design, data and methodology: This study uses a multivariate regression model to investigate the influence of WoM on consumer attitudes and consumer decision-making. It categorizes the quality of WoM into source level and acceptance level, to analyze its influence from a new perspective. A total of 400 surveys were completed, resulting in 336 usable questionnaires for analysis. It was collected in 14 cities from all regions in China. This study constructs a theoretical model of WoM influence on consumers' purchase willingness based on a systematic review of the related literature on WoM quality, perceived value, customer trust, and consumers' purchase willingness. Results: Empirical results reveal that the Internet WoM (consumer's source level and acceptance level) indirectly affects consumer behavior by influencing consumer attitudes. Conclusions: This study provides practical significance and value for merchants to develop better WoM marketing and to establish the reliability of WoM websites. Companies should consider online WoM from the perspective of consumers, thereby improving existing marketing strategies.