Luminescence properties, tunable emission and energy transfer of Na3Sc2(PO4)3: Sm3+, Bi3+ phosphors

Na 3 Sc 2 (PO 4 ) 3 :R (R = Bi 3+ , Sm 3+ , and Sm 3+ /Bi 3+ ) are successfully synthesized in air atmosphere. The high-temperature solid-state reaction method is used in this work. The X-ray diffractometer patterns confirm that all samples have the single pure phase Na 3 Sc 2 (PO 4 ) 3 . Na 3 Sc 2 (PO 4 ) 3 :Bi 3+ displays blue emission because of the Bi 3+ - Sc 3+ metal-to-metal charge-transfer and the 3 P 1  →  1 S 0 transition of Bi 3+ . Na 3 Sc 2 (PO 4 ) 3 :Sm 3+ shows red-orange emission with four emission bands derived from the 4 G 5/2  →  6 H 5/2 (550 - 582 nm), 6 H 7/2 (582–625 nm), 6 H 9/2 (625–675 nm), and 6 H 11/2 (675–750 nm) transitions of Sm 3+ . The optimal Sm 3+ concentration in Na 3 Sc 2 (PO 4 ) 3 :Sm 3+ is ∼8mol%. An adjustable color emission from blue to red-orange of Na 3 Sc 2 (PO 4 ) 3 :Sm 3+ , Bi 3+ with excitation at 345 nm can be observed when the ratio between Sm 3+ and Bi 3+ ions is changed. Na 3 Sc 2 (PO 4 ) 3 :Sm 3+ , Bi 3+ emits red–orange light under excitation 406 nm. The optimal Bi 3+ concentration in Na 3 Sc 2 (PO 4 ) 3 :8mol%Sm 3+ , Bi 3+ is ∼ 6mol%. The energy transfer from Bi 3+ to Sm 3+ in Na 3 Sc 2 (PO 4 ) 3 :Sm 3+ , Bi 3+ is verified by the spectral properties of samples. We discuss the influences of Bi 3+ or Sm 3+ concentration on luminescence properties of samples and analyze their luminous mechanism by energy level diagram. The experimental results of paper are useful for the research of new Bi 3+ and Sm 3+ doped phosphors.