Multiplication of electronic excitations in nanophosphors Lu 2O 3:Eu 3+ and Lu 2O 3:Tb 3+

Abstract

Luminescence properties of Lu 2O 3:Eu 3+ and Lu 2O 3:Tb 3+ nanocrystalline powders with the particle size varying from 46 to 6 nm were studied under excitation by synchrotron radiation in the photon energy range (up to ∼22.5 eV) covering the region where the processes of multiplication of electronic excitation occur. It was found that the excitation spectra of Tb 3+ emission from all Lu 2O 3:Tb 3+ nanopowders have similar behavior, whereas the shape of the excitation spectra of Eu 3+ emission from Lu 2O 3:Eu 3+ nanopowders strongly depends on the particle size. The difference in the behavior of Lu 2O 3:Eu 3+ and Lu 2O 3:Tb 3+ nanophosphor systems was explained by different mechanisms of the energy transfer from the host to Eu 3+ or Tb 3+ ions (either the hole or electron recombination mechanism, respectively), which are differently influenced by losses of electronic excitations near the particle surface.