In Situ Small-Angle Neutron Scattering Analysis of the Initial Deuteride Formation of Deuterium-Cerium Reactions under a Controlled Gas Flow

摘要

"Real-life" metals inevitably form the oxide layer, thus leading to complex initial hydriding processes, which are still unclear because of the experimental challenges in monitoring elemental steps including surface sorption, permeation, and concentration of hydrogen. In this study, the deuteride precipitation caused by the concentration of deuterium was successfully measured by the in situ small-angle neutron scattering (SANS) method, which used a self-designed reaction chamber to give rise to the scattering signals of the surface structure. In addition, in the measurements of activated cerium samples, surface sorption of deuterium could be modified to form a constant flow in order to further explore the initial hydriding processes. The formation of deuterides was found to occur as soon as deuterium was absorbed in the samples with a thin oxide layer and the subsequent growth of deuterides depended on the amount of consumed D-2. However, the sample with a thick oxide layer showed the delayed precipitation of deuterides and the decelerated subsequent growth of deuterides without inhibiting the surface absorption of deuterium. The in situ SANS method showed the high sensitivity to the deuteride phase on the surface at a deuterium amount of 0.2 mu mol cm(-2) D-2 for cerium and a great potential in exploring the mechanism of early incipient stages of hydrogen reactions.