Luminescence properties of Eu3+, Tb3+ or Tm3+ activated Ca4GdO(BO3)3 under X-ray and UV excitation

The X-ray and UV excited luminescence properties of Eu3+, Tb3+ and Tm3+ ions in the matrix of Ca4GdO(BO3)3 were investigated. Eu3+ and Tb3+ ions show high luminescence efficiency in emitting red and green color light for both under X-ray and UV excitation, respectively, while Tm3+ ion did not show high luminescence efficiency in emitting blue color light. The energy transfer from Gd3+ ion to Eu3+ or Tb3+ ion occurred for both under X-ray and UV excitation, while energy transfer from the Gd3+ ion to Tm3+ ion did not happen. The absorption spectra of Ca4GdO(BO3)3:RE (RE = Eu3+, Tb3+ and Tm3+) were studied, the host lattice related absorption band was located at 211 nm, the CT absorption band of Eu3+ ion and 4f → 5d transition absorption band of Tb3+ ion were both located at 258 nm.