Temperature-dependent phase transformation of TiO2 nanoparticles synthesized by sol-gel method

[Display omitted] •Sol-gel derived TiO2 nanoparticles are studied for their phase transformation.•X-ray diffraction patterns showed the strong Bragg peaks of anatase (101) and rutile (110) phases.•Raman spectroscopy demonstrated the phase transformation of TiO2 nanoparticles.•The estimated band gaps were 3.38/3.03 eV from the samples calcined at 450/700 °C.•Selected area diffraction patterns endorsed the polycrystalline nature of the samples. Nanocrystalline TiO2 particles were prepared to study the calcination temperature dependent phase transformation. X-ray diffraction (XRD) patterns showed the strong Bragg peaks correspond to anatase (101) and rutile (110) phases with their crystallite size 12 and 49 nm for the samples T1 and T2 calcined at 450 and 700 °C respectively. Raman spectroscopy investigation showed the phase transformation with the dominating rutile peaks from the pure-anatase phase. By UV–vis absorption spectroscopy, the strong ultraviolet-light absorption below 400 nm was observed. Using Kubelka-Munk function, the estimated band gap values were found to be 3.38 and 3.03 eV. The transmission scanning microscopy (TEM) images exhibited the slightly agglomerated nanoparticles while the selected area diffraction (SAED) patterns endorsed the polycrystalline nature.