Persistent luminescence and synchrotron radiation study of the Ca2MgSi2O7Ca2MgSi2O7:Eu2+,R3+Eu2+,R3+ materials

The tetragonal Ca2MgSi2O7Ca2MgSi2O7:Eu2+,R3+Eu2+,R3+ persistent luminescence materials were prepared by a solid state reaction. The UV excited and persistent luminescence was observed in the green region centred at 535 nm. Both luminescence phenomena are due to the same Eu2+Eu2+ ion occupying the single Ca2+Ca2+ site in the host lattice. The R3+R3+ codoping usually reduced the persistent luminescence of Ca2MgSi2O7Ca2MgSi2O7:Eu2+Eu2+, which differs from the M2MgSi2O7M2MgSi2O7:Eu2+Eu2+(M=Sr,Ba)(M=Sr,Ba) and MAl2O4MAl2O4:Eu2+Eu2+(M=Ca,Sr)(M=Ca,Sr) materials. Only the Tb3+Tb3+ ion enhanced slightly the persistent luminescence. With the aid of synchrotron radiation, the band gap energy of Ca2MgSi2O7Ca2MgSi2O7:Eu2+Eu2+ was found to be about 7 eV that is very similar to those of the M2MgSi2O7M2MgSi2O7:Eu2+Eu2+(M=Sr,Ba)(M=Sr,Ba) materials. Thermoluminescence results suggested that the R3+R3+ ions might act as electron traps, but only the TL peaks created by Tm3+Tm3+ and Sm3+Sm3+ can be found in the temperature range accessible. Lattice defects (e.g. oxygen vacancies) are also important, since the same main thermoluminescence peak was observed at about 100∘C with and without R3+R3+ codoping.