Dopant-free, polymorphic design of TiO sub(2 nanocrystals by flame aerosol synthesis)

A dopant-free aerosol synthesis of highly crystalline TiO sub(2 nanoparticles (20-35 nm) with tunable polymorphic content is demonstrated by rapid flame spray pyrolysis. By controlling precisely the total ambient oxygen partial pressure of the combustion in a quartz tube enclosure, anatase content as high as 96 wt% (4 wt% rutile) was obtained at high oxic flame conditions, while rutile content as high as 94 wt% (6 wt% anatase) was obtained under anoxic flames. The polymorphic variability lies within a narrow range of combustion equivalence ratios, that is, 1.0