X-ray diffraction study of nanocrystalline titania thin films prepared by pulsed laser deposition

Pulsed laser deposition of phase pure thin films of rutile and anatase from a rutile target is investigated. Rutile films prepared at the base pressure and at < or =473 K were amorphous and the crystalline quality was improved with increasing substrate temperature. The crystallite size was found to vary from 2 nm to 58 nm in the temperature range 573-973 K. Addition of oxygen has been found to be beneficial in promoting the formation of anatase phase even at a temperature of 673 K. From the base pressure to 10(-4) mbar, films were rutile, while at approximately 0.001 mbar, the rutile phase was found to transform to anatase. Rietveld analysis indicated about 20% of anatase and about 80% of rutile phase for the films prepared at 0.001 mbar of oxygen partial pressure. Good quality anatase films were formed at approximately 0.05 mbar, while the films were amorphous at higher partial pressures of oxygen.