L. N. Padurets

Isotope effect in the hydrogen distribution in the solid solution TiN0.40H0.19D0.19

AbstractThe structure of a solid solution with a combined isotope composition based on TiN0.40H0.19D0.19 (space group

Some lessons from the development of metal hydride chemistry in the light of hydrogen storage problems

P\overline 3 m1

Deuteron dynamics in the γ phase of titanium deuterides as probed by NMR

) has been studied by neutron diffraction. The isotope effect in the distribution of H and D isotopes has been found: the isotopes are located in tetrahedral interstices of the same type but with different z coordinates; there is splitting of 2d tetrahedral interstices into two groups, the protium (H) and deuterium (D). Therefore, in the ordered “layered” structure of the TiN0.40H0.19D0.19 solid solution, two different isotopes of the same element cannot be located at the same plane perpendicular to the threefold axis. The crystal-chemical analysis of the surroundings of H and D has been performed, and considerable differences have been revealed between the coordination polyhedra surrounding different hydrogen isotopes. It has been found that, in some metal-hydrogen systems, protium and deuterium should be treated as independent chemical components.

Determination of Arrangement of Hydrogen Isotopes in the Solid Solution Tin0.40H0.19D0.19 by Neutron Diffraction

Titanium deuterides TiD1.92, TiD1.98, and TiD2.0 have been studied by 2H and 47, 49Ti NMR in a magnetic field of 7.04 T and a temperature range of 120–500 K. At all temperatures and compositions, the 2H NMR line is a singlet described by the Gaussian function. The contribution of demagnetizing fields to the 2H NMR shift is ∼50 ppm. The titanium NMR spectra for all compositions comprise two signals due to the 47Ti and 49Ti isotopes. The shift between these signals depends on the deuterium content and temperature. The 47, 49Ti NMR line shape, width, and shifts have been considered in the framework of second-order quadrupole effects for a tetragonal lattice distortion and random distribution of vacancies. The Knight shifts σ(2H) and K(47, 49Ti) are a function of temperature with a clearly pronounced singularity at ∼300 K. The contact, orbital, and polarization contributions to the Knight shifts have been estimated from analysis of the temperature dependences of σ(2H) and K(47, 49Ti).

In memory of Alexey Lvovich Shilov (1.07.51–8.11.09)

The main trends of the chemistry of hydrides of transition metals and their alloys are briefly reviewed. “Sensational” hydrogen capacity data and the potential of some metal materials (metals, alloys, and quasi-crystals) and carbon nanomaterials in reversible hydrogen storage applications are critically analyzed. The significance of research in this field for hydrogen energy applications is underlined.

2 H and 47, 49 Ti nuclear magnetic resonance in the ? phase of titanium deuterid

Comparative analysis of metals (as well as their alloys and intermetallic compounds) and various carbon nanomaterials as working substances for hydrogen storage and transportation systems has been performed. It has been shown that, because of the fundamental difference in the nature of interaction with hydrogen of these two large classes of compounds, the fields of their application (as well as their performance) are certainly different. Some theoretical calculations and concepts concerning the hydrogen capacity of the materials under consideration have been critically surveyed.

2H and 47, 49Ti nuclear magnetic resonance in the gamma phase of titanium deuterides TiD x

Titanium deuterides TiDx (x = 1.92, 1.98, 2.0) and the Ti0.95Zr0.05D1.76 alloy were studied by 2H NMR in magnetic fields of 4.69 and 7.04 T in the temperature range 120–500 K. The correlation coefficients of deuteron self-diffusion calculated from the temperature dependence of the line width were described by the Arrhenius equation. The activation energies Ea and preexponential factors were determined. For the Ti0.95Zr0.05D1.76 alloy, the line width was found to depend on the magnetic field, which was explained by the fact that deuterons are in different environments formed by titanium and zirconium atoms.

ISOTOPIC EFFECT IN HYDROGEN AND NITROGEN SOLID SOLUTIONS IN α -Ti

By neutron structure analysis the crystal structure of the solid solution with the combined isotope composition on the base of titanium — TiN0.40H0.19D0.19 was studied (space group P3m1). It was found isotopic effect in distribution of the hydrogen isotopes H and D: the isotopes arrange over the same type of tetrahedral interstices but have different coordinates z, i.e. the splitting of a set of tetrahedral positions 2d into hydrogen (H) and deuterium (D) is observed. It follows from this that in the ordered “layered” structure of the solid solution TiN0,40H0,19D0,19 there can not be two different isotopes of the same element on one plane perpendicular to threefold axis. Crystal-chemistry analysis of environment of ? and D is carried out and the essential differences in coordination polyhedrons surrounding the two isotopes are revealed. Analysis of the results of the present work and also literary data shows that in a number of metal-hydrogen systems hydrogen and deuterium should be considered as independent chemical components.