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

The structure of a solid solution with a combined isotope composition based on TiN 0.40 H 0.19 D 0.19 (space group ) 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 2 d tetrahedral interstices into two groups, the protium (H) and deuterium (D). Therefore, in the ordered “layered” structure of the TiN 0.40 H 0.19 D 0.19 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.