Crystal structure and optical property of TiO2 gels and films prepared from Ti-edta complexes as titania precursors

Titania gel and films were prepared from Ti-edta complex solutions as new ceramic precursors, and their crystal structures and optical properties were investigated. Anatase appeared in the gel at firing temperatures between 450 and 500 °C, and was transformed to rutile at temperatures between 550 and 600 °C. This low transformation temperature is presumed to be due to the small crystalline size and micro pores in the gel. Refractive indices of the films were higher than those of the films prepared by a sol-gel process at firing temperatures above 700 °C. These high values were caused by the rutile phase in the TiO2 films.