Influence of acidic pH on the formulation of TiO 2 nanocrystalline powders with enhanced photoluminescence property

Abstract

Titanium dioxide (TiO₂) nanoparticles were prepared by the sol-gel method at different pH values (3.2-6.8) with a hydrochloric acid (HCl) solution. Raw samples were calcined at 500 °C for 2 h. The effects of pH on the structural, morphological and optical properties of TiO₂ nanoparticles were investigated. At pH 4.4-6.8, only the anatase phase of TiO₂ was observed. Under strong acidic condition at pH 3.2 rutile, brookite and anatase co-exist, but rutile is the predominant phase. The strain value increased and the crystallite size decreased as the HCl content increased. The increased crystallite sizes in the range 21-24 nm and enhanced blue emission intensity around 432 nm was obtained for the sample at pH 5.0. Experimental results showed that TiO₂ nanoparticles synthesized at pH 5.0 exhibited the best luminescence property with pure anatase phase.