Photoluminescence and Raman studies on tin dioxide powder and tin dioxide/single-walled carbon-nanotube composites

摘要

Photoluminescence (PL) and Raman spectroscopy were used to characterize the tin dioxide (SnO_2) powder and the SnO_2/ single-walled carbon-nanotube (SWCNT) composites. The SnO2 powder shows a strong PL broad band centered at 1.95 eV (635 nm) under excitation at 280 nm (4.43 eV) and four PL bands peaking at: 1.95 eV (635 nm), 2.67 eV (464 nm), 2.82 eV (439 nm), and 2.98 eV (416 nm) under excitation at 350 nm (3.54 eV). PL decay-time measurements of the SnO_2 powder indicates a PL lifetime of about 1.53 ns. In the SnO_2/ SWCNT composites, prepared mechanicochemically, a quenching of PL is observed as the concentration of SWCNT increases. The Raman spectra were recorded at two excitation wavelengths: 514.5 and 676.4 nm. At the excitation wavelength of 676.4 nm (1.83 eV), the Raman spectrum shows a narrowed asymmetric profile of the G band (~1585 cm~(-1)), which indicates that in the SnO_2/SWCNT composite there is an interaction between SnO2 and metallic SWCNTs.