Effect of Ag doping on the crystallization and phase transition of TiO2 nanoparticles

TiO2 nanoparticles doped with different Ag contents were prepared by a modified sol–gel method, using titanium tetraisopropoxide and silver nitrate as precursors and 2-propanol as solvent. Silver was incorporated into the TiO2 matrix via decomposition of AgNO3 during thermal treatment in different atmospheres. Effects of Ag doping on the crystallization and phase transition of the TiO2 nanoparticles were studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Raman spectroscopy techniques. While air annealing incorporates silver into TiO2 matrix in silver oxide form, annealing in nitrogen incorporates metallic silver into TiO2. Formation of silver oxide increases the thermal stability of the TiO2 particles. Silver oxide affects the crystallization process of TiO2 particles and the temperature of transition form anatase to rutile. On the other hand, presence of metallic silver in the samples annealed in nitrogen atmosphere decreases the temperature of phase transition of TiO2 nanoparticles.