Gd₂Si₂O₇:Ce (GPS:Ce) and (Gd,La)₂Si₂O₇: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 °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 °C sample showed the best thermo-stability. The three materials have potential application as a novel type of scintillator.

A new Sr-based borate Sr₃B₁₄O₂₄ with an unwonted 2D double layer and a short UV cutoff edge (<200 nm).