Luminescence and multi-step energy transfer in GdAl3(BO3)4 doped with Ce3+/Tb3+

Ce3+ and/or Tb3+ doped GdAl3(BO3)(4) phosphors were prepared via a high-temperature solid-state reaction method. The band gap of GdAl3(BO3)(4) is determined from the VUV excitation spectrum of a Ce3+ doped sample at 14 K and further confirmed by that of undoped and Tb3+ doped samples at RT. X-ray excited luminescence (XEL) of GdAl3(BO3)(4): Ce3+ was measured. The main electron-vibrational interaction (EVI) parameters for Ce3+ in GdAl3(BO3)(4) were simulated. The vacuum referred binding energy (VRBE) scheme of lanthanide 4f/5d states in GdAl3(BO3)(4) was constructed. Using this scheme, the lowest 5d excitation band of Pr3+ in GdAl3(BO3)(4) was predicted, showing that the estimation is in agreement with the experimental result. The occurrence of multi-step energy transfer processes which include Gd3+->+Ce3+, Gd3+-> Tb3+,Ce3+-> Tb3+, and Tb3+-> Gd3+, Tb3+-> Ce3+ under different excitations was derived from excitation, emission, and fluorescence decay spectra. (C) 2015 Elsevier B.V. All rights reserved.