Optical characterization of sol-gel-derived SnO2:Eu nanopowders annealed at high temperatures

Nanoparticulate SnO2 powders doped with europium (0.5 at%) were prepared by using sol‐gel method. The samples were sintered in air or argon at temperatures ranging from 600 to 1400 °C. Raman‐, SEM‐ and photoluminescence characterization of the samples was carried out. The heat‐treated samples exposed mainly broad emission bands typical of Eu3+ ions in disordered surrounding when excited at 464 nm (direct excitation of Eu3+) whereas spectrally well‐resolved emission characteristic of Eu3+ in crystalline phase was obtained when excited at 266 nm (attributed to host‐sensitization). The broad emission bands quite abruptly disappeared after annealing at 1400 °C. Inert gas (argon) atmosphere was found to improve the emission intensity compared to similar heat treatment in air. It is argued that the observed luminescence behaviour might be explained by the combined effect of the OH groups and the peculiarities of coarsening of the nanopowder induced by heat treatment. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)