Luminescence properties and energy transfer of CdWO4:Sm3+,Bi3+,M+(M=Li, Na, K) phosphors for white LEDs

Abstract A series of Sm 3+ –Bi 3+ co-doped CdWO 4 phosphors with wolframite structure have been prepared via a high temperature solid state reaction process and their structural and luminescence properties were thoroughly investigated. The color-tunable emission from blue to yellow can be realized by WO 6 –Sm 3+ or WO 6 –Bi 3+ –Sm 3+ energy transfer. A new distinct excitation bands from the CdWO 4 :Sm 3+ ,Bi 3+ phosphors are clearly observed at about 361 nm which comes from the 1 S 0 → 3 P 1 transitions of Bi 3+ . The Fluorescent Resonance Energy Transfer between Bi 3+ and Sm 3+ were considered to be the primary mechanisms and it was proved from their crystal structure. Based on the results in this study, CdWO 4 :Sm 3+ ,Bi 3+ ,K + sample is considered as an efficient phosphor with excellent color tunability for white UV-LEDs.