Synthesis and luminescent properties of KGd(MoO 4 ) 2 :Sm 3+ red phosphor for white light emitting diodes

Abstract The red-emitting phosphors of Sm 3+ ions doped KGd(MoO 4 ) 2 were synthesized by a high temperature solid state reaction method. The X-ray diffraction patterns confirmed that the principal crystalline phase of the sample was KGd(MoO 4 ) 2 . The photoluminescence (PL) excitation spectra of KGd(MoO 4 ) 2 :Sm 3+ showed a series of absorption peaks in the range of 300–500 nm and the strongest excitation peak at 406 nm due to 6 H 5/2 → 4 F 7/2 transition of Sm 3+ . The PL spectrum indicated that the optimum dopant concentration of Sm 3+ ion is 0.06. The critical transfer distance of Sm 3+ ions was 17.65 A and the quenching mechanism of KGd(MoO 4 ) 2 :Sm 3+ determined electric dipole–dipole interaction. The CIE chromaticity coordinates of the KGd(MoO 4 ) 2 :0.06Sm 3+ phosphor was located in the red region. All decay curves well fitted by the double exponential function, and average lifetimes for the 4 G 5/2 excited level of Sm 3+ in the KGd(MoO 4 ) 2 was in the submicrosecond. And the quantum efficiency was determined to be 28.5%.