NMR evidence for low-frequency local motion of H (D) atoms in TaV₂at low temperatures

Abstract

Measurements of the temperature dependence of the 1H, 2D and 51V spin lattice relaxation rates T1-1 in TaV2Hx (Dx) show a second low-temperature T1-1 maximum in addition to the usual maximum associated with H(D) diffusion. This feature can be attributed to low-frequency local motion of H(D) atoms. Strong effects of hydrogen isotope substitution are observed at low temperatures.

Hydrogen jump motion in Laves-phase hydrides: Two frequency scales

“…On the other hand, Bowman et al [4] have suggested the possibility of a coexistence of two hydrogen jump processes with different rates. The unambiguous evidence for a coexistence of two types of hydrogen jump motion with different characteristic frequencies has been found in the series of NMR experiments on the C15-type TaV 2 -H(D) system [6][7][8][9]. These experiments have revealed the temperature dependence of the nuclear spin-lattice relaxation rate R 1 with two well-separated peaks.…”

Nuclear magnetic resonance study of the low-temperature localized H(D) motion inα−ScHx(Dx)<

“…13,14 The maximum motional contribution to the low-temperature 51 V relaxation rate in the deuterides was found to be approximately three times higher than in the hydrides with nearly the same x values. These results were also interpreted 19 in terms of different fractions of atoms participating in the localized motion, the value of p for D being higher than that for H.…”

“…Such an additional lowtemperature maximum was observed for the 51 V spin-lattice relaxation rate in the Laves phase hydrides TaV 2 H x (D x ), which also shows fast localized H͑D͒ motion. 13,14 The results of our 45 Sc spin-lattice relaxation rate measurements for ␣-ScH x (D x ) at Sc /2ϭ86.2 MHz are shown in Fig. 1.…”

Ultrasonic study of hydrogen motion in a Ti-Zr-Ni icosahedral quasicrystal and a 1/1 bcc crystal approximant

“…For example, H diffusion in the polytetrahedral Laves phases has been studied extensively with a number of different experimental techniques. [9][10][11][12] The hydrogen motion in these intermetallic phases tends to be more complex than in simple metals due to the large number and variety of interstices. Icosahedral QC's are also likely dominated by tetrahedral order and thus provide a variety of sites and migration paths for interstitial hydrogen.…”