Effects of PVP on structure of TiO2 prepared by the sol-gel process

The synthesis of nanocrystalline TiO2 powders obtained from the hydrolysis of Ti(OBU)(4) in the presence of polyvinylpyrrolidone (PVP) was investigated. Porous titania with a Brunauer-Emmett-Teller surface area up to 65 m(2) g(-1) and distribution of pores in the range of mesopores were obtained after heat treatment at 500 degreesC devoted to the removal of PVP from TiO2/PVP composites. The influence of PVP on the phase transformation of TiO2 from anatase to rutile was investigated by using X-ray diffraction and Raman spectra. It was found that PVP could noticeably enhance the transformation by reducing the onset transformation temperature. The obtained powders were also characterized by differential scanning calorimeter, transmission electron microscopy and high-resolution electron microscopy. (C) 2001 Elsevier Science BN. All rights reserved.