Synchrotron Radiation Study of the M2MgSi2O7:Eu2+ Persistent Luminescence Materials

The synchrotron radiation luminescence and excitation spectra of the Eu2+ doped M2MgSi2O7 (M = Ca, Sr, Ba) materials were investigated at the SUPERLUMI station of HASYLAB at DESY, Germany. The measurement of the band gap (Eg) energy of all three host lattices using the excitation spectra of Eu2+ gave values around 7 eV. The measured band gap energies were very similar but slightly higher than those calculated with the DFT-methods. The effect of R3+ co-doping was studied at different temperatures between 10 K and room temperature. A significant increase in the band gap energy was observed with decreasing temperature. In contrast, no noteworthy change in this value was observed as a function of the R3+ co-doping ion