The effect of the post-annealing on the nanostructure and optical properties of SnO2

Nano-crystalline SnO2 particles have been synthesized by simple precipitation method using SnCl(4)5H(2)O and NH4OH as complexing. The structural properties of the prepared tin oxide nano-powders as prepared and annealed at temperatures 450 degrees C have been characterized by X-ray diffraction (XRD) and Scanning electron microscopy (SEM) analyses. The XRD patterns show pure tetragonal SnO2 phase and size of crystals increases by increasing the annealing temperatures. The samples where characterized by SEM to study the morphology of nanoparticles. The optical direct band gap values of SnO2 nanoparticles were calculated from diffuse reflectance spectra and for annealed sample it is about 4.07 eV. The value exhibit nearly a 0.5 eV blue shift from that of bulk SnO2 (3.6 eV), which is related to decrease in size of the particles.