Patent ID: 8178074

Claim:
A method for producing titanium oxide particles having a decahedral box-shape, and a particle diameter in a range of from 1 nm to 100 nm, by contacting a gas containing titanium tetrachloride vapor and an oxidizing gas containing water vapor, which produces the decahedral titanium oxide particles when the produced titanium oxide particles are randomly collected, and observed using an electronic microscope, at least 80% of titanium oxide particles, which can be observed in an arbitrary visual field, have the particle diameter of from 1 nm to 100 nm, wherein the method comprises a step of preheating the gas containing titanium tetrachloride and the oxidizing gas containing water vapor to 500° C. or greater followed by mixing the gas containing titanium tetrachloride vapor and the oxidizing gas containing water vapor to form a mixed gas, and introducing the mixed gas into a region which is heated to 800° C. or greater; the gas containing titanium tetrachloride vapor contains tetrachloride vapor and oxygen, the oxidizing gas containing water vapor is a mixed gas of water vapor and oxygen; and a molar ratio of O 2 /titanium tetrachloride in the gas containing titanium tetrachloride vapor is in a range of from 0.1 to 7.