Surface chemistry of surfactant AOT-stabilized SnO(2) nanoparticles and effect of temperature.

SnO(2).xH(2)O nanoparticles were prepared at room temperature by the microemulsion route. Sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was used as a surfactant to stabilize the nanoparticles. These nanoparticles show green luminescence at 510nm, which has been assigned to oxygen vacancies. Infrared spectra of samples heated in the temperature range 500-900 degrees C show bond formation between SnO(2) nanoparticles and SO(4)(2-), which arises from oxidation of SO(3)(-) present in AOT. This was further supported by X-ray diffraction. Shape transformations of the particles from triangular to spherical and then to rectangular was observed as the heat-treatment temperature was increased, and this is related to the surface energy of particles. An enhancement in emission intensity of Eu(3+) was observed when Eu(3+) ions were doped into the SnO(2) nanoparticles due to significant energy transfer from SnO(2) (or Eu-O) to Eu(3+) through surface-mediated energy transfer as compared to direct excitation of Eu(3+) at 397nm. Interestingly, these nanoparticles are dispersible in water, and can be incorporated into polymer-based materials such as polyvinyl alcohol to give homogeneous films, giving rise to blue and red emissions. Copyright 2010 Elsevier Inc. All rights reserved.