Uniform-size rutile TiO2 microrods were synthesized by simple molten-salt method with sodium chloride as reacting medium and different kinds of sodium phosphate salts as growth control additives to control the one-dimensional (1-D) crystal growth of particles. The effect of rutile and anatase ratios as a precursor was monitored for rod growth formation. Apart from uniform rod growth study, optical properties of rutile microrods were observed by UV-visible and photoluminescence (PL) spectroscopy. TiO2 materials with anatase and rutile phase show PL emission due to self-trapped exciton. It has been observed that synthesized rutile TiO2 rods show various PL emission peaks in the range of 400 to 900 nm for 355 nm excitation wavelengths. All PL emission appeared due to the oxygen vacancy present inside rutile TiO2 rods. The observed PL near the IR range (785 and 825 nm) was due to the formation of a self-trapped hole near to the surface of (110) which is the preferred orientation plane of synthesized rutile TiO2 microrods.
Keywords: TiO2 microrod; anatase; molten-salt method; photoluminescence; rutile.