Luminescent properties of Gd2SiO5 powder doped with Eu3+ under VUV-UV excitation

The luminescent properties of Gd2SiO5 powder crystals doped with Eu3+ were investigated using synchrotron radiation and a VUV laser (157.6 nm) as excitation sources. The excitation spectra in the range of 160-330 nm monitoring the red emission from Eu3+, ions reveal bands corresponding to intraconfigurational 4f-4f transitions of Gd3+ and charge transfer states (CTS) of Eu3+O2-, as well as interband transitions of the Gd2SiO5 host, indicating an efficient energy transfer process from the host or directly from Gd3+ to Eu3+ ions. The inspection of D-5(0) -> F-7(0) emission lines from Eu3+ ions suggests that there are three inequivalent sites for Eu3+ in this host. The excitation band around 215 nm and the unique emission features associated with this excitation band were attributed to one of the inequivalent Eu3+ sites, which exhibits an unusually weak coupling with host lattice. The energy levels of Eu3+ in the Gd2SiO5 host were tentatively assigned according to the laser excited emission spectra.