Effects on the size of nano-TiO2 powders prepared with sol–emulsion–gel method

Small and uniform nano-TiO2 particles were obtained by sol–emulsion–gel method. Optimum preparation conditions include the surfactant concentration at the critical micelle concentration (CMC) and the pH value at 8–9. The calcinations could improve the crystallization of TiO2 powders and accelerated the phase transformation from amorphous phase to anatase or rutile. Seen from the TEM, the spherical and uniform nano-TiO2 particles were obtained as calcined at 500 °C, and the gradual shape change of the particles in the process of calcination was noticed: Formed sphere → Rod → Sphere → Distorted sphere.