Quasielastic neutron scattering study of hydrogen motion in C15-type

In order to clarify the mechanism of hydrogen diffusion in cubic Laves phase , we have performed high-resolution quasielastic neutron scattering measurements on (x = 0.6 and 1.1) in the temperature range 10-320 K. It is found that the diffusive motion of hydrogen in this system can be described in terms of two jump processes: the fast localized H motion within hexagons formed by interstitial g sites and the slower hopping from one hexagon to the other. This model is also supported by neutron diffraction measurements showing that the sublattice of g sites in is split into hexagons well separated from each other. The behaviour of the elastic incoherent structure factor for suggests that only a fraction of the H atoms participate in the fast localized motion, and this fraction increases with temperature. Comparison of the properties of and other Laves phase hydrides with g-site occupation shows a clear correlation between the parameters of the two jump processes and the g-g distances (within the hexagons) and (between different hexagons).

[1]  R. Hempelmann.  Quasielastic Neutron Scattering and Solid State Diffusion , 2000 .

[2]  A. V. Skripov,et al.  Hydrogen diffusion in C15-type HfMo2H0.4: nuclear magnetic resonance evidence of two frequency scales of H hopping , 1999 .

[3]  S. I. Campbell,et al.  Quasi-elastic neutron scattering study of the hydrogen diffusion in the C15 Laves structure, TiCr1.85 , 1999 .

[4]  C. Karmonik,et al.  HYDROGEN MOTION IN C15-TYPE ZRMO2HX : QUASIELASTIC NEUTRON SCATTERING AND NUCLEAR-MAGNETIC-RESONANCE STUDIES , 1999 .

[5]  R. Hempelmann,et al.  Quasielastic neutron scattering study of hydrogen motion in C14- and C15-type ZrCr2Hx , 1999 .

[6]  M. Latroche,et al.  Hydrogen induced phase transitions in YMn2 , 1998 .

[7]  M. Conradi,et al.  NMR evidence for change in the local structure of ZrCr 2 H x , 1998 .

[8]  A. Podlesnyak,et al.  Neutron diffraction study of deuterium ordering in C15 type TaV2Dx (x>1) in the temperature range of 1.5–295 K , 1997 .

[9]  H. Wipf.  Hydrogen in Metals III , 1997 .

[10]  C. Karmonik,et al.  Localized motion of hydrogen in C15-type : a quasielastic neutron scattering study , 1996 .

[11]  J. Shinar,et al.  PULSED-FIELD-GRADIENT NUCLEAR MAGNETIC RESONANCE STUDIES OF HYDROGEN DIFFUSION IN LAVES-PHASE HYDRIDES , 1995 .

[12]  M. Latroche,et al.  Neutron diffraction study of YMn2Dx deuterides (1 ⩽ x ⩽ 3.4) , 1995 .

[13]  G. Majer,et al.  A pulsed-field-gradient NMR study of hydrogen diffusion in the Laves-phase compounds ZrCr2Hx , 1994 .

[14]  Rush,et al.  Dynamics of hydrogen in alpha -LaNi5 hydride investigated by neutron scattering. , 1994, Physical review. B, Condensed matter.

[15]  A. V. Skripov,et al.  Hydrogen mobility in the C15-type compounds ZrCr2Hx: proton spin relaxation study , 1993 .

[16]  T. Udovic,et al.  Anomalous hydrogen dynamics in rare earth metals , 1991 .

[17]  A. V. Skripov,et al.  Nuclear magnetic resonance study of hydrogen diffusion in HfV2Hx(Dx) and ZrV2Hx(Dx): effects of phase transitions and isotope substitution , 1991 .

[18]  A. V. Skripov,et al.  Nuclear magnetic resonance study of diffusion and localised motion of H(D) atoms in TaV2Hx(Dx) , 1990 .

[19]  M. Belyaev,et al.  LETTER TO THE EDITOR: NMR evidence for low-frequency local motion of H (D) atoms in TaV2 at low temperatures , 1989 .

[20]  Seymour,et al.  Low-temperature localized motion of hydrogen and electronic structure transition in hexagonal-close-packed scandium. , 1989, Physical review. B, Condensed matter.

[21]  R. L. Havill,et al.  Neutron Inelastic Scattering in the HfV2H3.3 Laves Phase Hydride* , 1989 .

[22]  M. Bee.  Quasielastic neutron scattering , 1988 .

[23]  W. Phillips.  Two-level states in glasses , 1987 .

[24]  K. Yvon.  Structural aspects of ternary metal hydrides: A critical review , 1984 .

[25]  V. Somenkov,et al.  Lattice structure and phase transitions of hydrogen in intermetallic compounds , 1984 .

[26]  R. Elliott,et al.  Correlated random walk in lattices: Tracer diffusion at general concentration , 1983 .

[27]  Louis Schlapbach,et al.  Hydrogen in Intermetallic Compounds , 1983 .

[28]  B. D. Craft,et al.  Diffusion behavior in titanium-chromium hydrides , 1983 .

[29]  R. Hempelmann,et al.  Hydrogen mobility in Ti1.2Mn1.8 hydride: A quasi-elastic neutron scattering study , 1982 .

[30]  J. Lynch,et al.  The solution of hydrogen in TaV2 , 1980 .

[31]  P. Fischer,et al.  The distribution of the deuterium atoms in the deuterated cubic laves-phase ZrV2D4·5 , 1979 .

[32]  P. Beck.  Metallurgy. (Physical Sciences and Engineering: Electronic Structure and Alloy Chemistry of the Transition Elements) , 1965 .

[33]  R. J. Elliott,et al.  Neutron Scattering from a Liquid on a Jump Diffusion Model , 1961 .