Quasielastic neutron scattering study of hydrogen motion in NbC0.71H0.28
In order to study the mechanism and parameters of H jump motion in the nonstoichiometric Nb carbides, we have performed quasielastic neutron scattering (QENS) measurements for NbC0.71H0.28 over the temperature range 11– 475 K. Our results indicate that about 30% of H atoms in this system participate in a fast diffusive motion. The temperature dependence of the corresponding H jump rate in the range 298–475 K follows the Arrhenius law with an activation energy of 328 ± 9 meV. The Q dependence of the QENS data suggests that the observed jump motion corresponds to long-range diffusion of H atoms along chains of the off-centre sites in carbon vacancies.
Hydrogen and deuterium in transition metal-p element compounds: Crystal chemical aspects of interstitial solid solubility and hydride phase formation
Abstract Compounds of transition metals with p elements of groups IIIb–VIIb which have been reported to exhibit hydrogen-absorbing properties are surveyed. Hydrogen is taken up only by those materials that have metallic properties or contain metal clusters with delocalized bonding. Almost all p elements can be constituents of these materials, and at least one transition metal component which is itself capable of dissolving hydrogen or forming hydride phases must be present. The crystallography of the hydride phases is presented and discussed with particular emphasis on results obtained by neutron diffraction methods. The hydrogen atoms are accommodated either in interstitial solid solutions with only minor changes in the host lattices or in new phases formed by major rearrangements of both transition metal and p element atoms. The distribution of the hydrogen atoms on the interstitial sites in the structures appears to be governed by two empirical rules: the hydrogen atoms are always more than 2 A apart and they preferentially occupy those sites that are most distant from the p element atoms.
Evaluation of Impact of Yarn Count and Stitch Length on Pilling, Abrasion, Shrinkage and Tightness Factor of 1 ? 1 Rib Cotton Knitted Fabrics
This study investigates the impact of yarn count and stitch length of 100% cotton knitted fabrics. 1 × 1 ribs structured fabrics were used in this research work. The stitch length 2.50 mm, 2.52 mm, 2.60 mm, 2.70 mm, 2.80 mm and 2.96 mm were used of the yarn count of 26Ne, 28Ne and 36Ne. The areal densities of the grey fabrics were in various amounts. The impacts of yarn count and stitch length were measured concerning pilling resistance, abrasion resistance, and shrinkage and tightness factor. The result showed that the fabric pilling grade decreased while number of cycle increased. Abrasion resistance decreased but length wise shrinkage increased despite the fact that the stitch length increased. The results also exposed that the tightness factor of the fabric increased with the increase of the stitch length in both dyeing and washing state and finished state compared to grey state for the yarn count 26Ne and homogeneous result not found for yarn count 28Ne and 36 Ne. Evaluation of Impact of Yarn Count and Stitch Length on Pilling, Abrasion, Shrinkage and Tightness Factor of 1 × 1 Rib Cotton Knitted Fabrics