Size and strain dependent anatase to rutile phase transition in TiO2 due to Si incorporation
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Powders with compositions Ti( 1−x )Si x O2 (where 0 ≤ x ≤ 0.25) were prepared to systematically study the effects of Si doping on anatase to rutile phase transformation. Samples were synthesized using a modified sol–gel route and were heat treated at various temperature in 450–950 °C range. XRD, Raman Spectroscopy, UV–vis spectroscopy, SEM, TEM were used to study the effects of dopant concentration and heat-treatments on the crystal structure, crystallite size and particle size. Rutile phase was found to occur only above a critical crystallite size. Si doping was found to delay the onset of anatase to rutile phase transformation from 500 °C (for composition x = 0) to 800 °C (for x = 0.25) through the lattice strain and crystallize size modification. Interplay between the average crystallite sizes, lattice strain, annealing temperature, and their effect on phase transition are discussed in terms of Si incorporation in lattice.
Principle investigator expresses sincere thanks to the Indian Institute of Technology, Indore, India for funding the research and using the Sophisticated Instrument Centre (SIC) and also Mr. Kinni Pandey for helping to us during measurement of FESEM data. We are also thankful to Dr. Pankaj Sagdeo for providing the valuable UV–Vis data.