Inelastic neutron scattering study of hydrogen in nanocrystalline Pd

The vibrational excitations and the position of hydrogen, in nanocrystalline Pd was investigated by neutron spectroscopy. This study was restricted to low hydrogen concentrations (less than or equal to 4.8 at%) where no hydrogen, precipitation was observed at room temperature. The experiments show that most of the hydrogen is incorporated in the grain boundaries and at the inner surfaces of the grains. Surface modes of the hydrogen can be identified. Compared to coarse-grained Pd, no change in the hydrogen solubility was found for the lattice regions of the nanocrystalline Pd.