New insights into the structural evolution of TiO2–Ti3O5–Ti2O3–TiO–TixOyCz–TiC systems at the nanoscale during the reduction process

Abstract

Titanium-based materials have been considered to be promising materials for many years. The structures and properties of Ti_xO_y and TiC at the nanoscale are important for studying the mechanism of formation of their nanoparticles. In this work, the density functional theory (DFT) method was used to calculate the structures of (Ti_xO_y)_n (n = 1–5) and (TiC)_n (n = 1–10) clusters. Based on these calculations, the formation pathways from (TiO₂)_n clusters to (TiO)_n and (TiC)_n clusters via carbon reduction were investigated. The results show that the pathway via (Ti₂O₃)_n or (Ti₃O₅)_n is the most likely pathway for the transformation of the (TiO₂)_n cluster to the (TiO)_n cluster. The (TiO)_n cluster is not the final product in the reduction process of (TiO₂)_n with C, and it can be finally transformed into (TiC)_n clusters via various Ti_nO_xC_y clusters via reaction with C. In addition, the (TiO₂)_n clusters can be transformed into (TiC)_n clusters directly via various Ti_xO_yC_z clusters.