Spin-lattice relaxation and mobility of protons in the lattice of the TiV0.8Cr1.2 alloy

Hydrogen diffusion in metal-hydrogen systems via NMR and DFT

“…However, upon increasing the hydrogen concentration, the T-sites occupancy become more and more favorable and for TiV 0.8 Cr 1.2 H 5.25 a very pronounced difference is noticed between DE T and DE O barriers, both values are significantly lower than those determined for the lowest hydrogen concentration. These results agree fairly with parallel neutron diffraction [52] and analysis of 1 H cw-NMR spectra [56]. Despite the presence of a local minimum energy at the O-site, its probability of occupancy must be rather low, and the lifetime of the hydrogen in the site is no longer enough to observe a resonance within the NMR experiment time.…”

“…4c and Refs. [56,57] and diffusion [58] measurements result in lower activation energy for the Cr-rich hydride, whereas the corresponding Q' 1 parameter is essentially greater as compared with TiV 0.8 Cr 1.2 H 5.29 (221 and 180 K, respectively). This disagreement is not completely understood.…”

“…4a [56,57]. As clearly seen, it consists of two lines, each from the other shifted narrow and broad signals, that corresponds to hydrogen atoms with different mobilities.…”

“…As clearly seen, it consists of two lines, each from the other shifted narrow and broad signals, that corresponds to hydrogen atoms with different mobilities. The spectral analysis proves that the broad component can be relied to hydrogen localized in T-sites of the bcc structure [56], whereas the narrow peak corresponds to a fast hydrogen motion. Obviously, at low temperature, when the hydrogen mobility is frozen, the intensity of the narrow component, which is proportional to the total number of hydrogen in the 'mobile' state, is equal to zero, whereas at high temperature, when all the hydrogen atoms are mobile, the broad line has disappeared.…”

1H NMR study of hydrogen self-diffusion in ternary Ti–V–Cr alloys

“…As it was shown in Refs. [6,15,16] it is possible to avoid the first two drawbacks by introducing a so-called exchange model. However, all these models contain a number of fitting parameters.…”