LUMINESCENCE EFFICIENCY OF CERIUM-DOPED INSULATORS - THE ROLE OF ELECTRON-TRANSFER PROCESSES

Insulating host materials doped with trivalent cerium show quantum eff iciencies of the Ce3+ emission ranging from zero to unity. Comparing o ptical and photoelectrical properties of a very efficient scintillator material (Lu-2(SiO4)O:Ce) to those of cerium doped oxides with quench ed emission, the radical differences for these materials are demonstra ted to originate from the location of the cerium energy levels with re spect to the host conduction band. Photoionization and subsequent nonr adiative relaxation processes responsible for the luminescence quenchi ng are discussed in a donor-acceptor model for the impurity ion and a rule for luminescence efficiency is derived, applicable to a variety o f phosphor and scintillator materials. (C) 1996 American Institute of Physics.