• Macromolecular Research
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• v.15 no.6
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• pp.553-559
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• 2007

Nanocomposite films were prepared by sol-gel synthesis from vanadium triisopropoxide with $poly((oxyethylene)_9$ methacrylate)-graft-poly(dimethyl siloxane), POEM-g-PDMS, producing in situ growth of vanadium oxide within the continuous ion-conducting POEM domains of micro phase-separated graft copolymer. The formation of vanadium oxide was confirmed by wide angle x-ray scattering (WAXS) and Fourier transform infrared (FT-IR) spectroscopy. Small angle x-ray scattering (SAXS) revealed the spatially-selective incorporation of vanadium oxide in the POEM domains. Upon the incorporation of vanadium oxide, the domain periodicity of the graft copolymer monotonously increased from 17.2 to 21.0 nm at a vanadium content 14 v%, above which it remained almost invariant. The selective interaction of vanadium oxide with POEM was further verified by differential scanning calorimetry (DSC) and FT-IR spectroscopy. The nanocomposite films exhibited excellent mechanical properties $(l0^{-5}-10^{-7}dyne/cm^2)$, mostly due to the confinement of vanadium oxide in the POEM chains as well as the interfaces created by the microphase separation of the graft copolymer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.634-637
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• 1999

The amorphous vanadium oxide as a cathode material is very preferable for fabricating high performance micro-battery. The amorphous vanadium oxide cathode is preferred over the crystalline form because three times more lithium ions can be inserted into the amorphous cathode, thus making a battery that has a higher capacity. The electrochemical properties of sputtered films are strongly dependent on the oxygen partial pressure in the sputtering gas. The effect of different oxygen partial pressure on the electrochemical properties of vanadium oxide thin films formed by r.f. reactive sputtering deposition were investigated. The stoichiometry of the as-deposited films were investigated by Auger electro spectroscopy. X-ray diffraction and atomic force microscopy measurements were carried out to investigate structural properties and surface morphology, respectively. For high oxygen partial pressure(>30% ), the films were polycrystalline V$_2$O$_{5}$ while an amorphous vanadium oxide was obtained at the lower oxygen partial pressure(< 15%). Half-cell tests were conducted to investigate the electrochemical properties of the vanadium oxide film cathode. The cell capacity was about 60 $\mu$ Ah/$\textrm{cm}^2$ m after 200 cycle when oxygen partial pressure was 20%. These results suggested that the capacity of the thin film battery based on vanadium oxide cathode was strongly depends on crystallinity.y.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.68-68
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• 2018

Nanoporous or nanotubular metal oxide can be fabricated by anodization of metal substrate in fluoride contained electrolytes. The approach allows various transition metals such as Zr, Hf, Nb, Ta to form highly ordered oxide nanostructures. These oxide nanostructures have various advantages such as high surface area, fast electron transport rate and slow recombination in semiconductive materials. Recently, vanadium oxide nanostructures have been drawn attentions due to their superior electronic, catalytic and ion insertion properties. However, anodization of vanadium metal to form oxide layers is relatively difficult due to ease formation of highly soluble complex in water contained electrolyte during anodization. Yang et al. reported $[TiF_6]^{2-}$ or $[BF_4]^-$ in electrolyte helps to formation of stable oxide layer [1, 2]. However, the reported approaches are very sensitive in other parameters. In this presentation, we deal with the other important key parameters to form ordered anodic vanadium oxide such as pH, temperatures and applied potential.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.156-161
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• 2008

The fabrication of vanadium oxide films directly on Si(100) substrates by plasma atomic layer deposition(ALD) with vanadium oxytriisopropoxide(VOIP) and oxygen as the reactants have been performed at temperature ranging from 250 to $450^{\circ}C$. Growth rate of vanadium oxide was $2.8{\AA}$/cycle at $300{\sim}400^{\circ}C$ defined as ALD acceptable temperature window, Vanadium oxide has been shown the different phases at $250^{\circ}C$ and more than $300^{\circ}C$. It has been confirmed that the phase of the films deposited at $250^{\circ}C\;was\;V_2O_5$ type and that of the films above $300^{\circ}C\;was\;VO_2(T)$ type measured at room temperature, respectively. A large change in resistance and small temperature hysteresis corresponding to a temperature has been observed in the vanadium oxide film deposited at temperature $350^{\circ}C$.

• The korean journal of orthodontics
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• v.24 no.1 s.44
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• pp.17-35
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• 1994

Vanadium is an essential trace element but has not been identified with a specific biogical role. To study the direct effects of vanadium on osteoblast, we incubated murin osteoblast-like (MC3T3-El) cells with various corcentration of vanadium oxide & sodium orthovanadate. This study was designed to investigate the effect of vanadium on DNA synthesis, alkaline phosphatase (ALP) activity, cAMP formation responsive to parathormone(PTH) and type I $\alpha$ 2 collagen ribonucleic acid (mRNA) level in murin osteoblast-like (MC3T3-El) cells. The cells were cultured in $\alpha-minimal$ essential medium$(\alpha-MEM)$ supplemented with $10\%$ fetal bovine serum (FBS) and then changed to $0.1\%$ FBS with various concenoation of vanadium oxide & sodium orthovanadate. Quiescent cultured MC3T3-El cells incubated for 24 hours with 2,5,10,15,20 ${\mu}M$ vanadium oxide incorporated $[^3H]Thymidine;$ every concentration showed increases in $[^3H]Thymidine$ incorporations dose dependant manner, the greatest response occurred at $20{\mu}M$. Quiescent cultured MC3T3-E1 cells incubated for 3days with 2,5,10,15,20 ${\mu}M$ vanadium oxide, for 2days with sodium orthovanadate and alkaline phosphatase was assayed with disodium phenyl phosphate as substrate. Vanadium oxide increased the alkaline phosphatase content in MC3T3-El cells at $2{\mu}M\;&\;6{\mu}M$ ; the greatest response occurred at $2{\mu}M$. But decreased at other content sodium orthovanadate increased alkaline phosphatase content in MC3T3-El cells at all concenoation ; the greatest response occurred at $4{\mu}M$. Quiescent cultured MC3T3-El cells incubated for 3days with $5,10{\mu}M$ vanadium oxide , with $5,8{\mu}M$ sodium orthovanadate and cAMP formation was measured by Radioimmunoassay(RIA). Vanadium oxide & sodium orthovanadate showed the tendency of inhibitory effects on cAMP responsiveness to PTH in MC3T3-El cells. Quiescent cultured MC3T3-El cells incubated for 24hours with $10,20{\mu}M$ vanadium oxide, with $5,10{\mu}M$ sodium orthovanadate and Type I $\alpha$ 2 collagen ribonucleic acid (mRNA) expression was studied by Nothern blot analysis. Northern blot analysis of vanadium oxide treated cells showed decreasing effects 0& sodium orthovanadate revealed increasing effects in type I $\alpha$ 2 collagen ribonucleic acid (mRNA) level.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.207-207
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• 2003

Uncooled infrared(IR) detectors that use a microbolometer with a large focal-plane array(FPA) have been developed with surface micromachining technology. There are many materials for microbolometers, such as metals, vanadium oxide, semiconductors and superconductors. Among theses, vanadium oxide is a promising material for uncooled microbolometers due to it high temperature coefficient of resistance(TCR) at room temperature. It is, however, is very difficult to deposit vanadium oxide thin films having a high TCR and low resistance because of the process limits in microbolometer fabrication. In general, vanadium oxides have been applied to microbolometer in mixed phases formed by ion beam deposition methods at low temperature with TCR in the range from -1.5 to -2.0%K.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.448-451
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• 2004

Vanadium oxides have been widely used in a variety of technological applications such electrochromic devices as infrared detectors and are expected as a material suitable for gas sensing applications. Thin films of Vanadium oxide (VOx) have been deposited by r.f magnetron sputtering under different oxygen partial pressure ratios and substrate temperatures. Humidity-sensitive properties of resistive sensors having interdigitated electrode structure are characterized. Our sensors show good response to humidity over 20%RH to 80%RH. Vanadium oxide films deposited with 0% $O_2$ partial pressure at foot exhibit greater sensitivity to humidity change than others.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.10
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• pp.475-480
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• 2006

Vanadium oxide thin films (VOx) have been deposited by RF magnetron sputtering from $V_2O_5$ target under different oxygen partial pressure ratios(0%, 10%) and substrate temperatures$(27^{\circ}C,\;400^{\circ}C)$. Crystallographic structure and morphology of the films are studied by XRD and SEM. Humidity-sensing properties of resistive sensors having interdigitated electrode structure are characterized through electrical conduction measurements. The films deposited at room temperature are amorphous whereas the ones deposited above foot are polycrystalline. The sensors show good response to humidity over 20%RH to 80%RH. Vanadium oxide thin films deposited with $0%O_2$ partial pressure at $400^{\circ}C$ exhibit greater sensitivity to humidity change than others.

• Journal of the Korean Vacuum Society
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• v.9 no.1
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• pp.42-47
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• 2000

The amorphous vanadium oxide thin films for thin-film rechargeable lithium batteries were fabricated by r.f. reactive sputtering at room temperature. As the experimental parameter, oxygen partial pressure was varied during sputtering. At high oxygen partial pressures(>30%), the as-deposited films, constant current charge/discharge characteristics were carried out in 1M $LiPF_6$, EC:DMC+1:1 liquid electrolyte using lithium metal as anode. The specific capacity of amorphous $V_2O_5$ after 200cycles of operation at room temperature was higher compared to crystalline $V_2O_5$. The amorphous vanadium oxide thin film and crystalline film showed about 60$\mu$Ah/$\textrm{cm}^2\mu\textrm{m}$ and about 38$\mu$Ah/$\textrm{cm}^2\mu\textrm{m}$, respectively. These results suggest that the battery capacity of the thin film vanadium oxide cathode strongly depends on the crystallinity.

• Bulletin of the Korean Chemical Society
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• v.19 no.8
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• pp.856-862
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• 1998

Vanadium oxide catalyst supported on ZrO2-WO3 was prepared by adding the Zr(OH)4 powder into a mixed aqueous solution of ammonium metavanadate and ammonium metatungstate followed by drying and calcining at high temperatures. The characterization of prepared catalysts was performed using solid-state 51V NMR and FTIR. In the case of calcination temperature at 773 K, for the samples containing low loading V2O5 below 18 wt % vanadium oxide was in a highly dispersed state, while for samples containing high loading V2O5 equal to or above 18 wt % vanadium oxide was well crystallized due to the V2O5 loading exceeding the formation of monolayer on the surface of ZrO2-WO3. The ZrV2O7 compound was formed through the reaction Of V2O5 and ZrO2 at 873 K and the compound decomposed into V2O5 and ZrO2 at 1073 K, which were confirmed by FTIR and 51V NMR.