SnO2 center dot 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 510 nm, which has been assigned to oxygen vacancies. Infrared spectra of samples heated in the temperature range 500-900 degrees C show bond formation between SnO2 nanoparticles and SO42-, which arises from oxidation of SO3- 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 Eu3+ was observed when Eu3+ ions were doped into the SnO2 nanoparticles due to significant energy transfer from SnO2 (or Eu-O) to Eu3+ through surface-mediated energy transfer as compared to direct excitation of Eu3+ 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. (C) 2010 Elsevier Inc. All rights reserved.