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. - Highlights: • The main EVI parameters for Ce³⁺ in GdAl₃(BO₃)₄ were simulated. • The VRBE scheme was constructed, thermal-quenching of Ce³⁺ luminescence was predicted. • Multi-step energy transfer processes occur under different excitations