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.