Preparation and characterization of pure anatase nanocrystals by sol–gel method

The nanocrystal particles with pure anatase phase were prepared by sol–gel method at the temperature of > 500 °C and characterized by TG-DTA, FT-IR, XRD, TEM and SAED. The combustion of gel powders, crystallization and phase transitions of the polymorphic phases TiO2 are discussed. The results show that the three allotropes of TiO2 form sequentially with the heating temperature increasing, which is different from many similar investigations that considered only the transition scheme “hydrous oxide gel–anatase–rutile”. The crystallization of anatase phase takes place at about 328 °C, and the phase stability region extended from 328 to 600 °C. The specimen has well crystalline morphology because of high crystallization temperature (550 °C) and the particle-size distribution ranging is between 20 and 30 nm.