Structural phase transition, grain growth and optical properties of uncompensated Ga-V co-doped TiO2

Abstract: Effect of uncompensated Ga-V co-doping on structural phase transition, grain growth process and optical properties of TiO2 is reported here. Inhibition of phase transition due to co-doping is confirmed by X-ray diffraction measurement. Activation energy of phase transition increases from 120KJ/mol (x=0) to 140 KJ/mol (x=0.046) due to Ga-V co-doping. In anatase phase, lattice constants increase 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 450-500 C. In anatase phase, strain increases due to co-doping which reduces crystallite size. In rutile phase, grain growth process is enhanced due to co-doping and particles show a rod-like structure with majority 110 facets. Bandgap decreases in both phases and reduced to a visible light region. BET analysis shows that surface area increases from 4.55 m2/g (x=0) to 96.53 m2/g (x=0.046) by Ga-V incorporation which provide a large number of active site for photocatalytic activity. Hence, co-doped anatase nanoparticle can be used as a promising candidate for photocatalytic applications using visible light up to a higher temperature ~650 C.