Characterization of Ag-TiO2 powders prepared by sol-gel process

In this study, microstructure and electrical properties of Ag-TiO2 powders, which were prepared by a simple sol-gel method, are investigated. The sol was prepared from titanium iso-propoxide, Ti(OC3H7)4 in iso-propanol (CH3CHOHCH3), used as solvent. AgNO3 was used as the precursor for Ag. For the structural studies, the corresponding gels were allowed to dry naturally for about seven days, dried in an oven at 180 °C for 30 min and then calcined at different temperatures (900, 1000 and 1100°C). The Ag-TiO2 nanoparticles were characterized using differential thermal analysis/thermal gravimetry, scanning electron microscopy, energy-dispersive X-ray analysis and X-ray diffraction. The results X-ray diffraction indicate that pure Ag and TiO2 powders are in rutile phase. However, calcination temperature had not significantly affected the crystalline structure of TiO2. Scanning electron microscopy images of powders show an aggregation of small spherical particles of dispersed sizes. Annealing of the Ag-TiO2 sample at high temperature produced more spherical particles, which aggregated to form bigger particles with porous structures. The electrical properties of the samples were measured using HMS-3000 Hall measurement system. The samples were found to be of n-type. The conductivity of TiO2 samples have been explicitly increasing with calcination temperature and with Ag doping