Luminescence properties of Gd2Si2O7:Ce and Gd2Si2O7:La, Ce under vacuum ultraviolet irradiation

The luminescence properties of Ce- or Ce and La-doped gadolinium pyrosilicate (Gd2Si2O7, GPS) were characterized using vacuum ultraviolet (VUV) excitation light. A prominent emission band was observed in the luminescence spectra with excitation at 60 nm and ascribed to 5d-4f transition of Ce3+. Because the excitation wavelength of 60 nm corresponded to the excitation in the host matrix, this result indicated that the excitation energy transfer occurred from the host matrix to Ce3+ ions. On the basis of the rise in the luminescence time profiles with excitation at 60 nm, the energy transfer occurred within 2 ns, which was much shorter than that of Ce-doped Gd2SiO5. For Ce-doped GPS, the decay rate was slower for the host excitation than that for direct excitation of Ce3+. In contrast, for Ce and La-doped GPS, no significant difference was observed for the host excitation and direct excitation of Ce3+. This result indicated that the energy transfer from the host to Ce3+ ions led to a different radiative decay process, and that La doping had an effect on the energy transfer and decay process.