Authors: Wei Chen Debraj Ghosh Shaowei Chen
Publish Date: 2008/08/01
Volume: 43, Issue: 15, Pages: 5291-5299
Abstract
Tin oxide nanoparticles were synthesized by electrochemical oxidation of a tin metal sheet in a nonaqueous electrolyte containing NH4F The asprepared nanoparticles were then thermally annealed at 700 °C for 6 h The resulting particles were characterized by a variety of experimental techniques including Xray diffraction XRD highresolution transmission electron microscopy HRTEM Raman UVvisible and photoluminescence PL spectroscopy The XRD patterns clearly showed that the amorphous phase of the assynthesized SnO2 particles was transformed into a rutiletype crystalline structure after thermal treatment and from the line broadening of the XRD peaks the average size of the annealed particles was found to be 154 125 118 nm for the particles initially synthesized at 20 30 and 40 V respectively Consistent results were also observed in HRTEM measurements which showed clear crystalline lattice fringes of the calcined nanoparticles as compared to the featureless profiles of the asproduced counterparts In Raman spectroscopic studies three dominant peaks were observed at 480 640 and 780 cm−1 which were ascribed to the E1g A1g and B2g Raman active vibration modes respectively and the wavenumbers of these peaks blueshifted with decreasing particle size Additionally a broad strong emission band was observed in roomtemperature photoluminescence measurementsThis work was supported in part by the National Science Foundation CHE0718170 and DMR0804049 The powder Xray diffraction data in this work were recorded on an instrument supported by the NSF Major Research Instrumentation MRI Program under Grant No CHE0521569 We thank the National Center for Electron Microscopy at Lawrence Berkeley National Laboratory for use of its facilities We also thank Prof J Z Zhang T Olson and R Newhouse UCSC for access to the Raman spectrometer and Prof S Oliver and D Rogow UCSC for assistance in XRD data acquisition
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