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

Abstract

SnO 2· xH 2O 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 510 nm, which has been assigned to oxygen vacancies. Infrared spectra of samples heated in the temperature range 500–900 °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 397 nm. 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.