ZrCo不均化における同位体効果

概要

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To understand hydrogen induced disproportionation of ZrCo, the kinetics and isotope effect were studied in isothermal and in heating-cooling cycle modes. Crystallographic change owing to the disproportionation was also examined with powder X-ray diffraction. The rate of disproportionation increased with a temperature up to 873K, but decreased at high temperatures. Similar temperature dependence was observed in the heating-cooling mode. The kinetics was analyzed following the method of Sharp et al. The analyses indicated that the reaction mechanism changed from R2 to F1 around 823K. The Arrhenius plots of the disproportionation rate gave activation energies of 154 and 159 kJ/mol for hydrogen and deuterium, respectively, and the frequency factor as 1.07 and 1.34x1010/s below 823K. However, the plots showed a negative activation energy for both hydrogens in the high temperature region, where a larger activation energy was suggested for deuterium than for Those characteristics were discussed by assuming the presence of an intermediate between the reaction and product.
富山大学の論文