A study on the structure, luminescence and thermo-stability of polycrystalline Gd2Si2O7:Ce and (Gd, La)2Si2O7:Ce

Gd2Si2O7:Ce (GPS:Ce) and (Gd, La)(2)Si2O7:Ce (La-GPS:Ce) phosphors with different crystal structures, tetragonal, orthorhombic and triclinic, were synthesized via a sol-gel technique. The prepared samples have been systematically investigated using room temperature (RT) XRD, high temperature (HT) XRD, HRTEM, selected area electron diffraction (SAED) and EDS elemental analysis. The results show that the phase transition occurred at 1350-1450 degrees C and the tetragonal phase was a low-temperature metastable phase and the orthorhombic and triclinic structures were stable at high temperatures. It was observed that the three structures display completely different luminescence efficiencies under both UV lamp and X-ray excitation, but the decay time was not strongly dependent on the crystal structure. The luminescence thermo-stability and activation energy were also measured and calculated. The results indicate that the thermo-stability was strongly dependent on the crystal structure and the GPS:Ce-1500 degrees C sample showed the best thermo-stability. The three materials have potential application as a novel type of scintillator.