Tunable Luminescence and Energy Transfer of Sr(3)B(2)O(6):Ce(3+), Sm(3+) Phosphors with Potential Anti-Counterfeiting Applications

Sm(3+) and Ce(3+) singly doped and Sm(3+) and Ce(3+) co-doped Sr(3)B(2)O(6) phosphors are prepared via a high-temperature solid-state reaction method. The crystal structure and phase purity are characterized by X-ray diffraction (XRD) analyses. The Sm(3+)-doped sample displays an emission in the orange-red region, with the strongest emission line at about 648 nm and possessing a good luminescence thermal stability between 78 and 500 K. With the increase in the Sm(3+) content, the concentration quenching is observed due to the cross-relaxation (CR) processes among the Sm(3+) ions. Upon 340 nm excitation, the Ce(3+)-doped phosphor presents a broad emission band in the blue region with a maximum at about 420 nm, which overlaps well with the (6)H(5/2) → (6)P(3/2) excitation line of Sm(3+) and implies the possible energy transfer from Ce(3+) to Sm(3+). The spectral and decay measurements of the Ce(3+) and Sm(3+) co-doped samples are conducted and the Inokuti–Hirayama (I-H) model is adopted to analyze the luminescence decay dynamics of the donor Ce(3+). Owing to the evident sensitization of the Sm(3+) by the Ce(3+) ions, the co-doped samples exhibit color variation under different wavelength excitations, endowing them with potential applications in optical anti-counterfeiting.