Synthesis and luminescence enhancement of CaY 0.6 (MoO 4 ) 1.9 :Eu 3+ red phosphors by Sm 3+ co-doping

Eu 3+ activated red phosphors based on the CaY x (MoO 4 ) 1.5x+1 (x = 0.2, 0.4, 0.6, 1, 2) as host materials were synthesized by using a combustion method. XRD analysis demonstrated that the synthesized samples matched with the standard card CaMoO 4 (JCPDS NO.77-2239) belonging to the tetragonal of the I4 1 /a space group. All samples showed several narrow sharp emission peaks under 393 nm n-UV excitation, the strongest of which was at 618 nm attributed to the 5 D 0 → 7 F 2 transition of Eu 3+. The optimal composition of the host was found to be CaY 0.6 (MoO 4 ) 1.9 (hereafter referred to as CYMO). After doping Sm 3+ into CYMO:Eu 3+ phosphor, the absorption peaks of Eu 3+ at 393 and 464 nm were broadened, and the peak intensity was also significantly higher than that of single-doped Eu 3+. The energy transfer phenomenon between Sm 3+ and Eu 3+ was discovered by the excitation and emission spectra in CYMO:Eu 3+,Sm 3+ phosphors, and verified by the fluorescence lifetime of Sm 3+ ions in the phosphors. The energy transfer mechanism between Sm 3+ and Eu 3+ is a dipole-dipole interaction, where the energy transfer efficiency in CYMO phosphor doped with 13% Eu 3+ and 3% Sm 3+ is 17.9%. The CIE coordinate and color purity were calculated as (x = 0.6598, y = 0.3388) and 93.72%, which indicated that the CYMO:13%Eu 3+,3%Sm 3+ phosphor is a red phosphor with excellent performance for potential application in n-UV light excited w-LEDs.