Stabilization of anatase phase by uncompensated Ga-V co-doping in TiO2: A structural phase transition, grain growth and optical property study.

Abstract

Uncompensated Ga-V co-doped TiO₂ samples have been prepared by modified sol-gel process. Inhibition of phase transition due to co-doping is confirmed by X-ray diffraction measurement. Activation of phase transition increases from 120 kJ/mol (x = 0) to 240 kJ/mol (x = 0.046) due to Ga-V incorporation. In anatase phase, lattice constant increases by the effect of Ga³⁺ interstitials.

This results in inhibition of phase transition. Anatase phase becomes stable up to ~ 650 °C in co-doped sample whereas for pure TiO₂ phase transition starts in between 450 and 500 °C. High-resolution transmission electron microscope image shows particle size decreases in anatase phase due to co-doping. Increasing strain due to Ga-V incorporation results in reducing crystallite size.

Brunauer–Emmett–Teller analysis shows that surface increases from 4.55 m²/g (pure TiO₂) to 96.53 m²/g (x = 0.046) by Ga-V incorporation. In rutile phase, grain growth process is enhanced mainly due to the effect of Vanadium and particles show a rod-like structure with majority {110} facets. Bandgap decreases in both phases and reduced to visible light region.

For charge balance in uncompensated Ga-V co-doped sample, structural distortion created in the lattice by combining effect of substitution, interstitials and oxygen vacancies, which results in stabilization of anatase phase and reducing of bandgap.

Citation

Khatun, N., Tiwari, S., Lal, J., Tseng, C.M., Liu, S.W., Biring, S. and Sen, S., 2018. Stabilization of anatase phase by uncompensated Ga-V co-doping in TiO2: A structural phase transition, grain growth and optical property study. Ceramics International.

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Category: Material & Chemical

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