Nanosize effect on phase transformations of titanium oxide Ti2O3

In situ studies of the thermal stability and transformations in titanium oxide Ti2O3 with corundum structure by using magnetic susceptibility method in the temperature range from 300 to 1200 K revealed that the crystal size had a large effect on the magnetic susceptibility value, structure and transformations in Ti2O3. Analysis of the experimental data showed that Ti2O3 microcrystals and nanocrystals were weak paramagnets; the value of magnetic susceptibility of microcrystals in absolute magnitude was twice as large as that for nanocrystals. The structure of Ti2O3 microcrystals remains stable during long-term annealing in vacuum, the crystal structure remains trigonal, and only the degree of Ti2O3 crystallinity changes. Vacuum annealing of nanocrystals in the temperature range from 300 to 1200 K demonstrated that the system was not stable: intermediate oxide Ti9O10 and Magneli phases Ti4O7, Ti4O7, Ti7O19 and Ti(3)O(5 )are formed depending on the annealing temperature. (C) 2019 Elsevier B.V. All rights reserved.