Structural Modifications and Associated Properties of Lanthanum Oxide Doped Sol−Gel Nanosized Titanium Oxide

Nanosized titanium oxide with and without addition of lanthanum oxide is prepared by the solution sol−gel method. Resultant gel precursor was characterized by thermal analysis and IR spectroscopy. The precursor gels were further calcined at various temperatures and then were subjected to measurement of the BET specific surface area, X-ray diffraction, and temperature-programmed desorption (TPD). The surface area of titanium oxide was increased from ≈1 m2/g to as high as 52 m2/g in the presence of 1% La2O3 at 700 °C. About 37% of the total pore volume was retained by La2O3 doping compared to pure titania at a calcination temperature of 700 °C. The shift of titania peak to a lower frequency region in the FTIR spectra indicates the Ti−O−La bond formation. TEM observation confirmed the nanocrystalline nature of sol−gel titania. The anatase−rutile transformation temperature increased to 850 °C in the presence of La2O3 from that of pure titania at 650 °C. The presence of La2O3 induces better surface acidity to ...