ABSTRACT
This chapter examines the phase transformation behavior of TiO2 nanopowders synthesized by the sol–gel method with reference to the influence of gas pressure on phase transformation kinetics. It explores the phase transformation effect by in situ synchrotron radiation diffraction by heating the material in a sealed capillary from 25 to 800°C. Over the temperature range examined, the pressure would have varied linearly from 0.10 to 0.36 MPa according to Gay-Lussac’s law. Increasing the oxygen partial pressure within the sealed capillary accelerates the amorphous-to-anatase transformation because of oxygen-rich environment but inhibits the anatase-to-rutile transformation because of the interstitial titanium formation, which inhibits TiO2 structure relaxation. Increasing the concentration of atmospheric oxygen is known to accelerate the amorphous-to-anatase transformation, whereas the formation of interstitial titanium in anatase may inhibit the anatase-to-rutile transformation. On this basis, the increase in oxygen partial pressure in the sealed capillary accelerated the transformation from amorphous TiO2 to crystalline anatase.
