Luminescence properties, tunable emission and energy transfer of Ca9MgLi(PO4)7:Bi3+/Eu3+ phosphor

Bi 3+ , Eu 3+ singly doped and Bi 3+ /Eu 3+ co-doped Ca 9 MgLi(PO) 7 (CMLPO) with a single pure phase are synthesized in air by high-temperature solid-state method and their crystal structure and the luminescence properties are investigated. CMLPO:Bi 3+ with excitation at 313 nm shows blue emission. CMLPO:Eu 3+ with excitation at 318 and 394 nm emits red emission. CMLPO:Eu 3+ , Bi 3+ with excitation at 318 nm shows an adjustable color emission when the ratio between Eu 3+ and Bi 3+ ions is changed. CMLPO:Eu 3+ , Bi 3+ under excitation 394 nm only emits a single red color light. The optimal Eu 3+ concentration in CMLPO:Eu 3+ and Bi 3+ concentration in CMLPO:8 mol%Eu 3+ , Bi 3+ are ∼8 mol% and 2 mol%, respectively. The luminescence intensity of CMLPO:Eu 3+ can be enhanced 1.4–2.2 times when Bi 3+ ion as sensitizer is co-doped into CMLPO:Eu 3+ . The energy transfer process in CMLPO:Eu 3+ , Bi 3+ is observed and analyzed. The luminous mechanisms of samples are explained by using the energy level diagrams of Eu 3+ and Bi 3+ ions. The research in this paper offers effective guidance for the optical property improvement of phosphors by co-doping other ions as sensitizer.