• Title/Summary/Keyword: 산소 분압

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Characteristics of Oxygen Permeation on $YBaCo_2O_{5+{\delta}}$ Ceramic Membrane ($YBaCo_2O_{5+{\delta}}$ 세라믹 분리막의 산소투과 특성)

  • Pyo, Dae-Woong;Kim, Jong-Pyo;Park, Jung-Hoon
    • Membrane Journal
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    • v.22 no.2
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    • pp.113-119
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    • 2012

  • $YBaCo_2O_{5+{\delta}}$ oxide was synthesized by solid state reaction and a typical dense membrane has been prepared using as-prepared powder by unilateral pressing and sintering at $1,180^{\circ}C$. The $YBaCo_2O_{5+{\delta}}$ membraneswas analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD analysis showed the double layered perovskite structure was observed over $1,150^{\circ}C$ without impurities. Oxygen permeation was measured in the temperature range from 750 to $950^{\circ}C$ according to oxygen partial pressure difference between feed and permeation side. The oxygen permeation flux increased with increasing temperature and oxygen partial pressure and the maximum oxygen flux of $YBaCo_2O_{5+{\delta}}$ membrane with 1.0 mm thickness was about 0.15 mL/$cm^2{\cdot}min$ at $950^{\circ}C$ and $PO_2$ = 0.42 atm. The activation energy for oxygen permeation decreased with decreasing oxygen partial pressure to be 76.0 kJ/mol at the condition of $PO_2$ = 0.21 atm.

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Cation Nonstoichiometry in CaTi$O_3$ (CaTi$O_3$에서 양이온 비화학양론)

  • Han, Yeong-Ho
    • Korean Journal of Materials Research
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    • v.2 no.3
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    • pp.207-212
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    • 1992

  • The defect structure of calcium titanates with CaO excess or $TiO_2$ excess was studied by measuring electrical conductivities as a funcition of oxygen partial pressure at $85O^{\circ}C$ to $1050^{\circ}C$. Execess CaO may divide itself equally between A and B sites, resulting in $Ca_{Ti}$" and Vo", while excess $TiO_2$ form $V_{Ca}$" and Vo". The equilibrium electrical conductivity data indicate that the solubilities of CaO and $TiO_2$ in $CaTiO_3$ are 5000ppm and 2000ppm, respectively. Oxygen vacancies contributed to the ionic conduction which flatten the conductivity minima and did not make any defect association with oppositely charged defects.ely charged defects.

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