Luminescent properties of GdTaO_4 and GdTaO4:Eu~(3+) under VUV-UV excitation

摘要

The luminescent properties of GdTaO_4 and GdTaO_4Eu~(3+) were investigated using synchrotron radiation VUV-UV source. Broad-band emissions peaked at 384 and 468 nm due to the TaO_4 group and ~6P_J→~8S_(7/2) emission of Gd~(3+) at 316 nm under the UV excitation are found at 20 K, hut quenched at room temperature. The excitation spectra of GdTaO_4:Eu~(3+) monitoring the ~5D_0 → ~7F_2 emission of Eu~(3+) comprise interband excitation of host, the TaO_4 group excitation, the CTS of Eu~(3+)-O~(2-) and Gd~(3+8)S_(7/2) → ~6I_J transitions. The energy-transfer processes among these centers are analyzed from the luminescence spectra. Under the VUV-UV excitation, GdTaO_4:Eu~(3+) shows a series of emission lines ascribed to the ~5D_J → ~7F_J transitions. The energy levels of Eu~(3+) in the GaTaO_4 host were tentatively assigned according to the emission spectra.