Debye-Waller factors of PdDx materials by neutron powder diffraction

Tetrahedral occupancy in the Pd-D system observed by in situ neutron powder diffraction

“…The issue is whether the t sites are also partially occupied under some or all circumstances. Our results are at odds with the existing literature reports based on neutron diffraction [2,5,[9][10][11][12], although it may be significant that ours is the first neutron diffraction study performed while executing a supercritical isotherm. Therefore, we address in turn our confidence in the results, secondly, the question of why t-site occupancy has never been substantiated previously, and thirdly, the circumstances under which hydrogen might feasibly occupy a t site.…”

The thermal properties of nanocrystalline Pd from 16 to 300 K

“…displacement value (u),, determined from the fit to eqn. (7) was 0055 0003 A for the nanocrystalline sample in the present case, compared with a value of 0.015 8, for the coarse-grained Pd data of Lawson et al (1992).…”

“…Values in the literature from neutron (Lawson et al 1992) and X-ray (Nelin 1971) diffraction studies of non-textured coarse-grained Pd powders are available, however, as are coarse-grained values from specific-heat measurements (International Tables for X-ray Crystallography 1968). Values from these other studies at the temperature extremes of the present investigation are listed in table 1 for comparison.…”

“…(7). From this process, a Debye temperature of 331 15 K was obtained for the nanocrystalline Pd sample, compared with similar values of 324 5 2 K (Lawson et al 1992) and 314 k 24 K (Nelin 1971) for coarse-grained Pd powder measured by neutron diffraction techniques. These characteristic temperatures are all somewhat higher than the value for Pd of 280 K derived from specific-heat measurements (Kittel 1971), but the difference is not surprising, since the different measurement techniques emphasize different portions of the phonon spectrum (Kolk 1984).…”

Direct observation of molten matter formation in the hydrogen-implanted subsurface of palladium

“…It is also unknown whether the amorphous molten matter was a chemical compound or not. To date, seven hydrides of Pd have been reported, including PdH 0.706 (Worsham et al 1957) and PdH (Lawson et al 1992). They are all crystalline, with their lattice parameters determined by X-ray diffraction and neutron diffraction, and therefore the molten matter is unable to be identified based on their crystallographical data.…”