Study on reflectivity and photostability of Al-doped TiO2 nanoparticles and their reflectors

The effect of Al doping on the reflective properties of TiO2 nanoparticles, synthesized by sol–gel method, has been investigated. It has been observed that with Al doping, the phase transition temperature for anatase to rutile phase increases; however, no change in morphology has been observed. No additional absorption edge was found in the absorption spectra, but a weak luminescent peak was noticed in the photoluminescence spectra. TiO2nanoparticles with 0.1% Al doping show higher photostability with practically no change in reflectance. A coating material has been prepared by dispersing these synthesized nanoparticles in water solution of organic binder. Coating material parameters such as pigment to binder weight ratio, solvent ratio, pH of solution have been taken into care to make the coating material flowable with good ability to adhere. Their coating was applied on a plastic substrate with different coating thicknesses to design light reflectors. These reflectors have been found to have diffuse reflectance of 98.17–98.29% for the 0.25-mm-thick coating.