Influence of calcination temperature on anatase to rutile phase transformation in TiO2 nanoparticles synthesized by the modified sol–gel method

Titanium dioxide (TiO2) nanoparticles with different ratios of anatase to rutile transformation were synthesized by the modified sol–gel method. The optical properties were investigated by UV–vis diffuse reflectance spectrophotometry. Phase transformation, crystallinity, and crystal structure of the calcined TiO2 samples were derived from X-ray diffraction analysis. The morphology and particle size of TiO2 were characterized by transmission electron microscopy (TEM). The Brunauer, Emmett and Teller (BET) adsorption–desorption of nitrogen gas for specific surface area determination at the temperature of liquid nitrogen was performed on TiO2 samples. TiO2 nanoparticles calcined at 400 °C for 3 h possessed the highest specific surface area of 97 m2 g− 1. The temperature of anatase to rutile transformation was found between 500 and 600 °C, and then completely transformed to rutile phase at 600 °C. Average particle sizes of the nanoparticles were in the range of 10–50 nm at calcination temperature between 400 and 600 °C. At higher temperature clearly favored particles growth and agglomerates are corresponded to decrease specific surface area.

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► The mixed-phase of TiO2 nanoparticles were prepared by the modified sol-gel method.
► The using of cellophane membrane improved ability to obtain small particles size.
► The transformation of anatase to rutile was found between 500 and 600 °C.