TRANSMISSION ELECTRON-MICROSCOPY STUDIES OF NANOPHASE TIO2

The chemical and microstructural properties of nanosized TiO2, obtaine d by sol-gel procedure, were investigated. The samples were characteri zed 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, de pended on the temperature of TiO2 preparation. In the temperature rang e between 293 and 820 K the TiO2 grains consisted of anatase, as the d ominant phase, and brookite. High resolution electron microscopy showe d 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, fr om 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 broadeni ng.