Persistent luminescence of Ba 2MgSi 2O 7:Eu 2+

Abstract

Ba 2MgSi 2O 7:Eu 2+,R 3+ (R=Y, La–Nd, Sm–Lu) materials were prepared with a solid state reaction. The UV excited ( λ exc = 355 nm ) and persistent luminescence bands of Ba 2MgSi 2O 7:Eu 2+ were both centered at 500 nm and thus they are due to the same Eu 2+ ions. The Tm 3+ co-doping induced by far the strongest enhancement of the persistent luminescence intensity and duration. The next strongest enhancement was achieved by the Er 3+, Nd 3+ and Pr 3+ co-doping. The enhancement by the remaining R 3+ co-doping ions was quite similar. The decay of the persistent luminescence consists of at least three processes. First process is very fast whereas the lifetime of the second process is in the range from 3.7 to 9 min depending on the co-doping ion. For the Pr 3+, Nd 3+, Er 3+ and Tm 3+ co-doped materials a third process with a lifetime varying from 14 to 28 min is observed. The persistent luminescence is suggested to involve lattice defects, i.e. oxygen (cation) vacancies, which create trapping levels for electrons (holes). The details of the mechanism(s) are still, however, under further investigations.