Site symmetry and host sensitization-dependence of Eu real time luminescence in tin dioxide nanoparticles.

The present work gives a detailed investigation of the dependence of the real time luminescence of Eu-doped tin dioxide nanopowder on rare earth (RE) site symmetry and host defects. Ultrafast time-resolved analysis of both RE-doped and undoped nanocrystal powder emissions, together with electronic paramagnetic resonance studies, show that host-excited RE emission is associated with RE-induced oxygen vacancies produced by the non-isoelectronic RE-tin site substitution that are decoupled from those producing the bandgap excited emission of the SnO matrix. A lower limit for the host-RE energy transfer rate and a model for the excitation mechanism are given.