High temperature stability of nanocrystalline anatase powders prepared by chemical vapour synthesis under varying process parameters

Systematic variation in the high temperature stability of nanocrystalline anatase powders prepared by chemical vapour synthesis (CVS) using titanium (IV) isopropoxide under varying flow rates of oxygen and helium was obtained by progressively shifting the decomposition product from C3H6 to CO2. The as-synthesised powders were characterised by high temperature X-ray diffraction (HTXRD), simultaneous thermo-gravimetric analyses (STA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). It was observed that the anatase to rutile transformation temperature progressively increased for samples synthesised at higher O2/He flow rate ratios. The improved anatase stability was attributed to the presence of incorporated carbon within the titania structure and confirmed by a high temperature carbon desorption peak.