Conceptual Design of Yttrium Oxyhydrides: Phase Diagram, Structure, and Properties

The synthesis of stable yttrium oxyhydride-type compounds raised a principal question regarding the key factors that may be responsible for formation routes and structural features of these attractive materials. For solving this challenge, the interplay between chemical composition and crystalline architectures has been theoretically explored via modeling structural transformations caused by the gradual oxidation of the host metal hydride system. The close combination of group-theory methods, mixed-anion chemistry arguments, and relevant density functional theory calculations provided us with the opportunity to suggest and characterize the candidate models for most probable stoichiometric versions of yttrium oxyhydrides. The predicted chemical compositions along with the crystallization results have been summarized in the phase diagram. It is shown that the cation–ligand interaction governs the structural stability which is achieved by matching favorable crystallographic positions of the oxygen and hydrogen atoms at the metal center