Effect of Pd ion doping in the band gap of SnO2 nanoparticles: structural and optical studies

Pd ion doping has influenced the band gap of SnO2 nanoparticles. Undoped and Pd ion-doped SnO2 nanoparticles were synthesized by chemical co-precipitation method. A tetragonal phase of SnO2 with a grain size range of 7–13 nm was obtained (studied by X-ray diffraction and transmission electron microscopy). A decreasing trend in the particle size with increasing doping concentration was observed. The presence of Pd in doped SnO2 was confirmed by chemical analysis carried out by energy-dispersive spectroscopy in the transmission electron microscope. Diffuse reflectance spectra showed a blue shift in absorption with increasing palladium concentration. Band gap of SnO2 nanoparticles was estimated from the diffuse reflectance spectra using Kubelka–Munk function and it was increasing with the increase of Pd ion concentration from 3.73 to 4.21 eV. The variation in band gap is attributed predominantly to the lattice strain and particle size. All the samples showed a broad photoluminescence emission centered at 375 nm when excited at 270 nm. A systematic study on the structural and optical properties of SnO2 nanoparticles is presented