Isotope Effects of Hydrogen Ion Transport in SrCeO_3(+Y_2O_3) and its Applications

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A research on the isotope effects in transport of hydrogen through the solid electrolyte SrCe_<0.95>Yb_<0.05>O_<3-6> was performed and the following results were obtained.1. On the measurement of electrical conductivity, an isotope effect was observed in the conditions where the proton conduction is dominant. The ratio of conductivity of proton to deuteron was ROO<2> which is normal difference estimated from the theory of classical kinetics.2. The solubility of hydrogen was measured by Sieverts method. The value was found very large compared to other oxides. The isotope effect in the solubility of hydrogen was not detected.3. The chemical diffusion coefficient was obtained from the solubility measurements. The isotope effect was also not detected. It was considered that the effect was reduced by the mechanism of ambipolar diffusion with oxygen ion vacancy.4. A new mechanism of solution of hydrogen was found in the condition of low oxygen chemical potential with the measurements of thermal desorption analysis.5. The permeation of hydrogen through the thin wall of the sample with and without electrolysis was studied and its phenomena was analyzed based on the model of defects. The ratio of permeated light hydrogen to heavy one was found 1.9 without electrolysis and was found 3.5 with electrolysis. These large isotope effects are not explained from the difference of their mobilities. The difference of the speed of electrode reaction was suggested as the reason of these phenomena.The possibility of this electrolyte as the material of membrane for the separation of isotope of hydrogen was ascertained from above results.