• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제13권9호
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• pp.751-757
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• 2000

The r.f. power effect for Pt doping is investigated on structural and electrochemical properties of amorphous vanadium oxide(V$_2$O$_{5}$) film, grown by direct current (d.c.) magnetron sputtering. Room temperature charge-discharge measurements based on a half-cell with a constant current clearly indicated that the Pt doping could improve the cyclibility of V$_2$O$_{5}$ cathode film. Using glancing angle x-ray diffraction(GXRD) and high-resolution transmission electron microscopy (HRTEM) analysis, we found that the Pt doping with 10W r.f. power induces more random amorphous structure than undoped V$_2$O$_{5}$ film. As the r.f. power of Pt target increases. large amount of Pt atoms incorporates into the amorphous V$_2$O$_{5}$ film and makes $\alpha$-PtO$_2$microcrystalline phase in the amorphous V$_2$O$_{5}$ matrix. These results suggest that the semiconducting $\alpha$-PtO$_2$ microcrystalline phase in amorphous matrix lead to a drastically faded cyclibility of 50W Pt doped V$_2$O$_{5}$ cathode film. Possible explanations are given to describe the Pt doping effect on cyclibillity of the amorphous V$_2$O$_{5}$ cathode film battery. film battery.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.889-892
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• 2000

We have investigated the Pt doping effect on structural and electrochemical properties of amorphous vanadium oxide film, grown by radio frequency magnetron sputtering. Room temperature charge-discharge measurements based on a half-cell with a constant current clearly indicated that the Pt doping could improve the cyclibility of V$_2$O$_{5}$ cathode film. Using glancing angle x-ray diffraction (GXRD) and high resolution transmission electron microscopy (HRTEM) analysis, we found that the Pt doping with l0W r.f. power induce more random amorphous structure than undoped V$_2$O$_{5}$ film. As the r.f. power of Pt increases, large amount of Pt incorporates into amorphous V$_2$O$_{5}$ and makes PtOx microcrystalline phase in amorphous matrix. This result suggests that the semicondcuting PtOx microcrystalline phase in amorphous matrix lead to a drastically faded cyclibility of 50W Pt doped V$_2$O$_{5}$ cathode film. Possible explanations are given to describe the Pt doping effect on cyclibility of vanadium oxide cathode film.de film.

• Electrical & Electronic Materials
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• 제9권7호
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• pp.690-695
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• 1996

We have systematically investigated the characterization of V$_{2}$O$_{5}$ thin films as a counter electrode for lithium based complementary electrochromic devices. The V$_{2}$O$_{5}$ thin films were prepared by thermal vacuum evaporation with varing the substrate temperature and film thickness. In electrochromic devices for smart windows, the WO$_{3}$ thin films with 400-800 nm thickness require to be capable of reversibly injection 10-15 mC/cm$^{2}$ of lithium, which is readily accomplished charge-balanced switching in a V$_{2}$O$_{5}$ thin films with 100-150nm thick. The V$_{2}$O$_{5}$ thin films produces considerably small changes in optical modulation properties in the visible and near infrared region(500-1100 nm) compared to the amorphous WO$_{3}$ thin films on 10-15 mC/cm$^{2}$ of lithium injection and the V$_{2}$O$_{5}$ thin films can therefore act as a counter electrode to WO$_{3}$ in a lithium based complementary clectrochromic devices. After 10$^{5}$ coloration/bleaching switching time, the degradation does not occurs and the devices exhibit a stable optical modulation in V$_{2}$O$_{5}$ thin films. It has shown that the injected lithium ion amounts in crystalline V$_{2}$O$_{5}$ thin films with the same thickness is large by 3-5 mC/cm$^{2}$ of lithium compared to the amorphous thin films in the same driving conditions. Therefore, to optimize the device performance, it is necessary to choose an appropriate film thickness and crystallinity of V$_{2}$O$_{5}$ for amorphous WO$_{3}$ film thickness as a working electrode.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제24권5호
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• pp.202-206
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• 2014

In order to investigate the photoluminescence (PL) properties of $V_2O_5$ films, amorphous and crystalline films were prepared by using RF sputtering system, and the PL spectra of the films were measured at the temperatures ranging from 300 K to 10 K. In the amorphous $V_2O_5$ film grown at room temperature, a PL peak centered at ~505 nm was only observed, and in the crystalline $V_2O_5$ film, two peaks centered at ~505 nm and ~695 nm, which is known to correspond to oxygen defects, were revealed. The position of PL peak centered at 505 nm for both the amorphous and crystalline $V_2O_5$ films showed a strong dependence on temperature, and the positions were 2.45 eV at 300 K and 2.35 eV at 10 K, respectively. The PL at 505 nm was due to the band energy transition in $V_2O_5$, and also, the reduction of the peak position energy with decreasing temperature was caused by a decrement of the lattice dilatation effect with reducing electron-phonon interaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.797-800
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• 2002

Instead of a solution process producing amorphous $LiV_3O_8$ form, we prepared Lithium vanadate glass by melting $Li_2O-P_2O_5-V_2O_5$ and $Li_2O-P_2O_5-Bi_2O_3-V_2O_5$ composition in pt. crucible and by quenching on the copper plate. From the crystallization of $Li_2O-P_2O_5-V_2O_5$ and $Li_2O-P_2O_5-Bi_2O_3-V_2O_5$, we could abtain glass-ceramics having crystal phase, LiV3O8 from glass matrix. The material heat-treated at lower-temperature, $250^{\circ}C$ had less crystalline and lower capacity, But the material heat-treadted at higher-temperature, $330^{\circ}C$ had higher capacity and $Li_2O-P_2O_5-V_2O_5$ glass-ceramics had higher capacity than $Li_2O-P_2O_5-Bi_2O_3-V_2O_5$ glass-ceramics.

• Journal of the Korean Ceramic Society
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• 제38권1호
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• pp.100-105
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• 2001

An all solid-state thin film battery (TFB) was fabricated by growing, undoped and Pt-doped vanadium oxide cathode film ( $V_2$ $O_{5}$ ) on I $n_2$ $O_3$: Sn coated glass, respectively. Room temperature charge-discharge measurements based on Li/Lipon/ $V_2$ $O_{5}$ full-cell structure with a constant current clearly shows that the Pt-doped $V_2$ $O_{5}$ cathode film is superior, in terms of cyclibility. X-ray diffraction (XRD) results indicate that the Pt doping process induces a more random amorphous structure than an undoped $V_2$ $O_{5}$ film. In addition to its modified structure, the Pt-doped $V_2$ $O_{5}$ film has a smoother surface than the undoped sample. Compared to an undoped $V_2$ $O_{5}$ film, the Pt doped $V_2$ $O_{5}$ cathode film has a higher electron conductivity. We hypothesize that the addition of Pt alters electrochemical performance in a manner of making more random amorphous structure and gives an excess electron by replacing the $V^{+5}$. Possible mechanisms are discussed for the observed Pt doping effect on structural and electrochemical properties of vanadium oxide cathode films, which are grown on I $n_2$ $O_3$: Sn coated glass.

• Korean Journal of Materials Research
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• 제5권7호
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• pp.802-807
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• 1995

The electrochromic properties of vacuum deposited V$_2$O$_{5}$ thin films as a function of crystallinity and film thickness have been systematically investigated. The as-deposited films have slightly yellow appearance. V$_2$O$_{5}$ films deposited at higher substrate temperature(>14$0^{\circ}C$) are found to be crystalline while those deposited at low substrate temperature are amorphous. The optical modulation on lithium ion injection indicates that V$_2$O$_{5}$ films exhibit anodic coloration in the 300~500 nm wavelength range and cathodic coloration in the 500~1100nm wavelength range independent of crystallinity and film thickness. The optical band gap energy of crystalline and amorphous Li$_{x}$ VV$_2$O$_{5}$ films shifts to higher energies by 0.17 eV and 0.75 eV, respectively, with increasing lithium ion injection up to x=0.6. The coloration efficiency of amorphous Li$_{x}$ V$_2$O$_{5}$ exhibits very little dependence on film thickness and lithium ion injection amounts in the near-infrared while it increases significantly with increasing film thickness and decreasing lithium ion injection amounts in the blue and near-UV due to the shift in absorption edge below around 500nm. However, the coloration efficiency of crystalline Li$_{x}$ V$_2$O$_{5}$is relatively independent of film thickness and lithium ion injection in the 300~1100 nm wavelength range.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.1018-1021
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• 2001

1018-1021 The CuO-P$_2$O$_{5}$ containing P$_2$O$_{5}$ as glass-former were prepared by press-quenching method on the copper plate. By post-heat treatment of these glasses, the CuO-P$_2$O$_{5}$ -V$_2$O$_{5}$ -g1ass ceramics was obtained and the crystallization behavior and dc conductivities were investigovted. The heat-treated glass-ceramics decreased in electrical conductivity by the order of 10$^1$ compared to amorphous glass. The linear relationship between In($\sigma$T) and T$^{-1}$ indicated that electrical conduction in CuO-P$_2$O$_{5}$ -V$_2$O$_{5}$ -gass occurred by a small polaron hopping.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1994년도 추계학술대회 논문집
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• pp.28-31
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• 1994

We have investigated the characterization of $V_2O_{5}$ thin films as a counter electrode for lithium based complementary electrochromic devices. The amorphous $V_2O_{5}$ thin films produces comparatively small changes in transmittance in the visible and near infrared compared to the crystalline $V_2O_{5}$ thin films, while the degradation occurs in a-$V_2O_{5}$ thin films with increasing the cycle life time. As the thickness of $V_2O_{5}$ thin films increases from 100 to 600 nm, the magnitude of transmittance modulation decreases. The crystalline $V_2O_{5}$ thin films with thickness around 1000 have electrochromic properties suitable for counter electrode application in lithium based electrochromic smart windows.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.733-736
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• 2001

Instead of a solution technigue producing amorphous LiV$_3$O$_{8}$ form, we prepared Lithium vanadate glass by melting Li$_2$O-P$_2$O$_{5}$-V$_2$O$_{5}$, composition in pt. crucible and by quenching on the copper plate. From the crystallization of Li$_2$O-P$_2$O$_{5}$-V$_2$O$_{5}$, we could abtain crystal phase, LiV$_3$O$_{8}$. The material heat-treated at lower-temperature, 25$0^{\circ}C$ was less crystalline, but had higher capacity. In present paper, we describe eletrochemical properties during crystallization process and find the best crystallization condition of Li$_2$O-P$_2$O$_{5}$-V$_2$O$_{5}$ glass as cathod material.cathod material.