Luminescent properties of GdTaO4 and GdTaO4 : Eu3+ under VUV–UV excitation

The luminescent properties of GdTaO4 and GdTaO4:Eu3+ were investigated using synchrotron radiation VUV–UV source. Broad-band emissions peaked at 384 and 468 nm due to the TaO4 group and 6PJ→8S7/2 emission of Gd3+ at 316 nm under the UV excitation are found at 20 K, but quenched at room temperature. The excitation spectra of GdTaO4:Eu3+ monitoring the 5D0→7F2 emission of Eu3+ comprise interband excitation of host, the TaO4 group excitation, the CTS of Eu3+–O2− and Gd3+8S7/2→6IJ transitions. The energy-transfer processes among these centers are analyzed from the luminescence spectra. Under the VUV–UV excitation, GdTaO4:Eu3+ shows a series of emission lines ascribed to the 5DJ→7FJ transitions. The energy levels of Eu3+ in the GaTaO4 host were tentatively assigned according to the emission spectra.