• Title, Summary, Keyword: Phosphosilicate gel

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Proton Conducting Behavior of a Novel Composite Based on Phosphosilicate/Poly(Vinyl Alcohol)

  • Huang, Sheng-Jian;Lee, Hoi-Kwan;Kang, Won-Ho
    • Journal of the Korean Ceramic Society
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    • v.42 no.2
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    • pp.77-80
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    • 2005
  • A series of proton conductive composite membranes based on poly(vinyl alcohol) and phosphosilicate gels powders were successfully prepared. The proton conductivity of these composite was attributed to the phosphosilicate gel, which derived from tetraethoxysilane and phosphoric acid by sol-gel process at a molar ratio of P/Si = 1.5. The proton conductivity increased with increasing both the content of phosphosilicate gel and relative humidity. Temperature dependence of conductivity showed a Vogel-Tamman-Fulcher type behavior, indicating that proton was transferred through a liquidlike phase formed in micropores of phosphosilicate gel. The high conductivity of 0.065 S/cm with a membrane containing 60 wt$\%$ of the gel was obtained at $60^{\circ}C$ at $90\%$ relative humidity.

Study on Sol-Gel Prepared Phosphosilicate Glass-Ceramic For Low Temperature Phosphorus Diffusion into Silicon

  • Kim, Young-Sig
    • Transactions on Electrical and Electronic Materials
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    • v.2 no.2
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    • pp.32-36
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    • 2001
  • A new solid source for low temperature diffusion into silicon was developed. The source wafer consists of an “active” compound, which is sol-gel prepared phosphosilicate glass-ceramics containing 56% P$_2$O$\sub$5/, embedded in a skeletal foam-like, inert substrate. Phosphorus diffusion from the new solid sources at low temperatures (800-875$^{\circ}C$) produced reprodecible sheet resistances and shallow junctions. From a series of one hour doping runs, the life time of the phosphosilicate source was determined to be over 40 hours. The effective diffusion coefficient of phosphorus into silicon and the corresponding activation energy at 850$^{\circ}C$ were determined to be 7.5${\times}$10$\^$-15/ $\textrm{cm}^2$/sec and ∼3.9 eV, respectively.

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The Kinetics of Volatilization of P2O5 From Sol-Gel Derved Phosphosilicate Glass-Ceramic Powder (졸-겔법으로 제조된 Phosphosilicate 유리-요업체 분말로부터 $P_2O_5$ 휘발 반응 속도론)

  • ;Richard E, Tressler
    • Journal of the Korean Ceramic Society
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    • v.29 no.2
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    • pp.89-94
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    • 1992
  • The kinetics of volatilization of phosphorous oxide from phosphosilicate glassceramic powders prepared by a sol-gel process were investigated at a given temperature. The rate of P2O5 vaporization increased with the P2O5 concentration in the phosphosilicate powder. Vaporization from the powder containing 46% P2O5 was analyzed using a kinetic model for diffusion limited evaporation. The diffusion through phosphosilicate glass in the surface of each particle in the temperature range 800~85$0^{\circ}C$ are presented.

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Preparation and Characterization of Proton Conductive Phosphosilicate Membranes Based on Inorganic-Organic Hybrid Materials

  • Huang, Sheng-Jian;Lee, Hoi-Kwan;Kang, Won-Ho
    • Bulletin of the Korean Chemical Society
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    • v.26 no.2
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    • pp.241-247
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    • 2005
  • A series of proton conductive inorganic-organic hybrid membranes doped with phosphoric acid ($H_3PO_4$) and/or triethylphosphate (PO(OEt)$_3$) have been prepared by sol-gel process with 3-glycidoxypropyltrimethoxysilane (GPTMS), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) as precursors. High proton conductivity of 3.0 ${\times}$ $10^{-3}$ S/cm with composition of 50TEOS-30GPTMS-20APTES-50$H_3PO_4$ was obtained at 120 ${^{\circ}C}$ under 50% relative humidity. Thermal stability of membrane was significantly enhanced by the presence of SiO$_2$ framework up to 250 ${^{\circ}C}$. XRD revealed that the gels are amorphous. IR spectra showed a good complexation of $H_3PO_4$ in the matrix. The conductivity under 75% relative humidity was significantly improved by addition of APTES due to the increase in concentration of defected site in hybrid matrix. The effect of PO(OEt)$_3$, humidifying time, and heat-treatment were also investigated. PO(OEt)$_3$ had no improvement on conductivity and conductivity increased with humidifying time, however, decreased with heating temperature.