抄録
Titanium dioxide nano-particles were synthesized by in-flight oxidation of micron-scale titanium nitride powder using inductive thermal plasma. The structure and phase composition of products depended on the oxygen flow rate, and the oxygen partial pressure. We investigate the formation mechanism of anatase and rutile, and the effect of additive hydrogen in thermal plasma. With the high oxygen flow rate, titanium nitride became fully oxidized and melted to TiO2 melts, leading to the spherical anatase single crystal. The vaporized species from the oxidized surface caused the formation of nanopowders with diameter of ave. 50nm, and the formation mechanism of nanopowders is associated to the composition of gas mixtures of TiO(g) and TiO2(g). Under higher O2 input conditions, TiO2(g) species is more stable than TiO(g), thus the oxygen-rich clusters grow to anatase nanopowder. Introduction of hydrogen enhanced the reduction of TiO2 species and the formation of oxygen-deficient clusters, leading to rutile nanopowder.
