Abstract

TiO_2 nanopowder has been synthesized by means of the flame method using a precursor of titanium tetraisopropoxide (TTIP, Ti(OC_3H_7)_4). In order to clarify the effect of cooling rate of hot flame on the formation of TiO_2 crystalline phases, the flame was controlled by varying the mixing ratio and the flow rate of gases. Anatase phase was predominantly synthesized under the condition having the steep cooling gradient in flame, while a slow cooling gradient enabled to form almost rutile TiO_2 nanopowder of above 95%.

• Keywords: Nanopowder;Flame temperature;Cooling gradient;Cooling rate;Anatase phase;Rutile phase;