Phase Transformations and Crystallization Kinetics of Electrospun TiO2 Nanofibers in Air and Argon Atmospheres

Titanium dioxide (TiO₂) is one of the most widely studied materials due to its high photoactivity, photodurability, mechanical robustness, low cost, and chemical and biological inertness. The optimum composition in terms of the anatase and rutile levels for maximum photocatalytic performance can be achieved by thermal annealing. In general, anatase forms amorphous TiO₂ at low temperatures, which subsequently transforms to rutile at higher temperatures. The transformation is affected by various conditions, which include the synthesis method, the amount of impurities, temperature, calcination time, and atmosphere type. This chapter investigates the effect of air and argon atmospheres on the transformation of anatase to rutile and the in situ crystallization kinetics of TiO₂ nanofibers using synchrotron radiation diffraction over the temperature range of 25–900°C. The electrospun TiO₂ nanofibers were initially amorphous but crystallized progressively to anatase and rutile at elevated temperatures. In air, anatase was first observed at 600°C and rutile at 700°C, but in argon both appeared at 700°C.