Abstract:
Possible models of the arrangement of hydrogen atoms at the sites of the cubic lattice of titanium oxyhydride TiO$_y$H$_p$ with vacancies in the metallic and nonmetallic sublattices are considered. It was found that titanium oxyhydride retains the B1 type crystal lattice of the initial cubic titanium monoxide TiO$_y$ and contains structural vacancies in the metal and oxygen sublattices. Comparison of the found analytical expressions for the intensity of diffraction reflections with experimental X-ray and neutron diffraction data showed that interstitial H atoms in oxyhydrides occupy vacant octahedral positions 4$(b)$ of the oxygen sublattice. No displacement of H atoms in tetrahedral positions 8$(c)$ is observed. A disorder-order phase transition channel associated with the formation of an ordered monoclinic titanium oxyhydride of the Ti$_5$O$_5$ type was found. The distribution functions of Ti, O, and H atoms in the partially ordered monoclinic oxyhydride TiO$_{0.96}$H$_{0.14}$ (Ti$_{0.89}$O$_{0.85}$H$_{0.12}$) with a Ti$_5$O$_5$-type structure are calculated for the first time, and the concentrations of these atoms at the positions of its lattice were found.
Keywords:titanium monoxide, hydrogen, nonstoichiometry, vacancies, octahedral and tetrahedral positions, distribution function.
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