Change in the Composition of Solid Nonstoichiometric Compounds by Ion Transfer Method

The paper presents results of measuring electron and ion transfer numbers of titanium hydride, carbide, and nitride. It is shown that these compounds had mixed electron-ionic (anionic) conductivity. The dependences of the ion transfer number on the nonmetal content in titanium carbide and nitride were obtained, and the change of the nonmetal content under the influence of an electric field was studied. The nonmetal atoms in nonstoichiometric titanium carbide and nitride were located in the octahedral voids of the titanium cubic lattice, forming a nonmetal sublattice. Nonstoichiometric titanium hydride had a fluorite-type cubic crystal lattice, and the hydrogen atoms were located in the tetrahedral voids of the cubic titanium lattice. In titanium boride, ionic conductivity appeared near compounds of stoichiometric composition. It is shown that the formation of interstitial phases corresponded to the Hegg criterion. Owing to the existence of vacancies in the nonmetal sublattice, ion transfer was possible under the influence of an electric field, resulting in a change in chemical composition of nonstoichiometric compounds. Analysis of the physicochemical properties of nonstoichiometric transition metal compounds was carried out as an opportunity to detect the ionic conductivity of carbides, nitrides, and oxides.