Stabilization of anatase by tungsten introduced to the titania lattice by sol-gel and impregnation techniques

Stable tungsten-doped titania sols have been prepared by a modified sol-gel process These were dried to gels and the resulting powders calcined from 200 to 1000 degrees C. Phase analysis was performed using Powder X-Ray Diffraction. Dopant concentrations from 1 to 10 metal atom percent were observed to stabilize the low temperature anatase phase of TiO2 to temperature as high as 900 degrees C. The stabilizing effect of tungsten in the titania lattice was also observed for samples doped by impregnation. The presence of tungsten in the anatase phase of titania was seen to maintain smaller primary particle size compared to undoped samples during calcination. Differential Scanning Calorimetric studies were used to monitor the commencement of the brookite to rutile phase transformation at the surface of TiO2.