BEGIN:VCALENDAR VERSION:2.0 PRODID:Data::ICal 0.22 BEGIN:VEVENT DESCRIPTION:Maiko Kofu\, JPARC\, Japan\n\n
The behavior of hydrogen in metals has attracted much attention in fundamental and applied research areas. Palladium hydrid e (PdHx) is a typical metal-hydrogen system and has been studied for many decades. Pd has remarkable abilities to absorb plenty of H atoms and the H atoms are highly mobile in the Pd lattice. It is interesting to examine h ow the properties are changed as the particle size is reduced to a nanomet er-scale. We have investigated structure\, diffusion and vibrational dynam ics by means of neutron scattering techniques for both bulk and nanocrysta lline PdHx with a diameter of 8nm. Neutron diffraction work on nanocrystal line sample demonstrated that some of hydrogen atoms are accommodated at t he tetrahedral (T) sites. This is in contrast to bulk PdHx with octahedral (O) occupation. In quasielastic scattering measurements\, we found an add itional fast diffusion process with a small potential barrier in nanocryst alline PdHx. Furthermore\, our inelastic scattering works revealed that na nocrystalline PdHx exhibits two distinct vibrational excitations\; one res embles that observed in bulk PdHx and the other is the excitations appeare d at higher energies. The additional diffusion process and vibrational sta tes are attributed to the H atoms at T sites near the surface of nanoparti cles. The potential shape around the T site near the surface will be discu ssed in the seminar.
\n DTSTART:20170907T150000Z LOCATION:Physics Building\, Room 313 SUMMARY:Structure and dynamics of hydrogen in nanocrystalline palladium END:VEVENT END:VCALENDAR