Luminescence properties of Sn1-xFexO2 nanoparticles

Nanoparticles of Sn1-xFexO2 (x = 0, 0.02, 0.05, 0.1) have been prepared by co-precipitation method using SnCl2 and FeSO4 precursors and subsequent heat-treatment at 600 degrees C. X-ray Diffraction (XRD) study shows that these nanoparticles crystallise in tetragonal system. The unit cell volume increases slightly with Fe2+ doping indicating substitution of Sn4+ sites by Fe2+ ions. The unit cell volume increases from 72.24 angstrom(3) to 72.90 angstrom(3) as x varies from 0 to 0.1. With increasing Fe2+ concentration, the peaks in X-ray diffraction pattern become broad because of strain effect produced from substitution of smaller ionic radius Sn4+ (0.69 angstrom) by large one Fe2+ (0.77 angstrom). The average crystallite size was found to decrease from 21 nm to 11 nm as x changed from 0 to 0.1. In Transmission Electron Microscopy (TEM) study of pure SnO2, the particles are spherical in shape and particle size is found to be 25 nm, which is close to 21 nm from XRD study. Its Selected Area Electron Diffraction (SAED) confirms the tetragonal system. In infrared study, a broad peak centred around 650 cm(-1) was observed due to Sn-O/Fe-O vibration. From steady state luminescence study, it is found that pure SnO2 and Fe2+ doped SnO2 show the band-edge emission around 400 nm and the emission intensity decreases with increasing Fe2+ concentration. The band-edge absorption occurs in 300-350 nm.