Transmission electron microscopy studies of nanophase TiO2

The chemical and microstructural properties of nanosized TiO2, obtained by sol-gel procedure, were investigated. The samples were characterized by analytical electron microscopy combining electron diffraction, high resolution electron microscopy and atomic force microscopy. These methods were supported by X-ray diffraction and thermal analysis. The chemical and structural properties, as well as the size of grains, depended on the temperature of TiO2 preparation. In the temperature range between 293 and 820 K the TiO2 grains consisted of anatase, as the dominant phase, and brookite. High resolution electron microscopy showed that the sample heated at 573 K had grain sizes from 2 to 10 nm, the average being (5 +/- 1) nm, and the pore sizes from 4.5 to 12 nm. The sample heated at approximate to 820 K revealed larger grain sizes, from 7 to 12 nm, the average being (9 +/- 1) nm, and the pore sizes from 6 to 10 nm. These values were confirmed by X-ray diffraction broadening.