Sans measurement of deuterium trapping at dislocations and grain boundaries in palladium

Abstract

Small angle neutron scattering (SANS) measurements have been made on deformed single crystal and polycrystalline palladium with and without deuterium dissolved in the solution phase at room temperature. The net scattering cross section for the same sample with and without deuterium loading shows a behavior expected from deuterium correlation with dislocations forming rod-like scattering structures. We conclude from these scattering measurements that the trapped deuterium is within 2-3 Burgers vectors of the dislocation core. On average 1-3 deuterons per A are trapped at dislocations in the deformed samples. The measurements indicate the straight, rod-like correlation geometry extends on average 50-100 A along the dislocations. Net scattering from a well annealed polycrystalline palladium sample exhibiting a behavior expected from surfaces has been observed. This net scattering is attributed to deuterium trapped at grain boundaries in the polycrystalline sample. A value of 0.4 +/- 0.2 trapped deuterons per A2 of grain boundary area is calculated from the well annealed polycrystalline scattering measurement.