Determination of arrangement of hydrogen isotopes in the solid solution TiN0.40H0.19D0.19 by neutron diffraction

Abstract

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 H 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.