Energy transfer between Eu3+ ions in a lattice with two different crystallographic sites: Y2O3:Eu3+, Gd2O3:Eu3+ and Eu2O3

Abstract

The Eu3+ ion occupies two different crystallographic sites in (Y1−xEux)2O3 and (Gd1−xEux)2O3, with site symmetry S6 and C2. Energy transfer over more than 7 Å occurs from Eu3+ (S6) ions to Eu3+ (C2) ions. This is shown to be a direct one-phonon assisted process, in combination with a one-site resonant two-phonon assisted process at higher temperatures. For x = 1 there is energy migration over the Eu3+ (C2) sublattice to quenching impurities. The presence of cooperative absorption points to superexchange interaction between the Eu3+ ions.