CHEMISTRY AND MATERIAL SCIENCE

Effect of high pressures and high temperatures on the structure of nanostructured titanium monoxide

A. A. Valeeva^ab, M. G. Kostenko^b, A. Pfitzner^c, A. A. Rempel<sup>ba

a</sup> Ural Federal University named after the first President of Russia B. N. Eltsin, 91, Mira st., Ekaterinburg, 620002, Russia
^b Institute of Solid State Chemistry UB RAS, 91, Pervomaiskaya st., Ekaterinburg, 620990, Russia
^c Institute of Inorganic Chemistry, Regensburg University, Regensburg, Germany

Abstract: The structure of nanostructured titanium monoxide TiO$_{0.98}$ containing structural vacancies in two sublattices simultaneously has been modified via thermobaric annealing. Analysis of the experimental data on thermobaric synthesis of nanostructured TiO$_{0.98}$ with cubic $B1$ type structure at temperatures $573$–$2273$ K and pressure $6$ GPa revealed that a transition from the cubic $B1$ (sp. gr. $Fm\overline{3}m$) phase to the trigonal Ti$_2$O$_3$ (sp. gr. $R\overline{3}c$) phase takes place in the nanostructured monoxide as a result of high pressures and high temperatures. The first-principle calculations of the cohesive energy and electronic structure show that the trigonal phase with space group $R\overline{3}c$ is energetically favorable compared to the cubic phase of the same composition TiO$_{3/2}$ and the orthorhombic ordered Ti$_2$O$_3$ (sp. gr. $Immm$) phase.

Keywords: nanostructured titanium monoxide, structural vacancy, nonstoichiometry, high pressure, high temperature, phase transition, electronic structure.

PACS: 61.72.Dd, 61.72.Bb, 64.70.Nd, 71.20.Ps

Received: 25.05.2018
Revised: 12.07.2018

Language: English

DOI: 10.17586/2220-8054-2018-9-4-544-548

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