PREPARATION, CHARACTERIZATION AND SURFACE-STRUCTURE OF COPRECIPITATEDHIGH-AREA 2-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1) POWDERS(X(0)

Powders with composition SrxTiO2+x (x = 0, 0.02, 0.11, 0.42 and 1) hav e been prepared by coprecipitation from strontium hydroxide and titani um isopropoxide and have been characterized after drying at 393 K, and after calcination at 773 and 973 K, using XRD, TG-DTA, BET surface ar ea and porosity measurements, FTIR-FTFIR and FT-Raman skeletal vibrati onal characterization, diffuse reflectance UV-VIS spectroscopy and FTI R spectra of the hydroxy groups and of adsorbed pyridine and CO2. Stro ntium was found to inhibit anatase crystallization, sintering and tran sformation to rutile. Strontium tended to be deposited at the surface of anatase and gave rise to a decrease of the surface acidity and an i ncrease of surface basicity. Moreover, it shifted the absorption edge of anatase to higher energies. For x = 1, the truly cubic SrTiO3 perov skite phase was produced at room temperature with high surface area. T he surface of SrTiO, was definitely basic, with only strontium and oxy gen ions exposed at the surface, and hydrogen impurities in the bulk.