Synthesis and luminescence enhancement of CaY0.6(MoO4)1.9:Eu3+ red phosphors by Sm3+ co-doping

Eu3+ activated red phosphors based on the CaYx(MoO4)(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 CaMoO4 (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 D-5(0)-> F-7(2) transition of Eu3+. The optimal composition of the host was found to be CaY0.6(MoO4)(1.9) (hereafter referred to as CYMO). After doping Sm3+ into CYMO:Eu3+ phosphor, the absorption peaks of Eu3+ at 393 and 464 nm were broadened, and the peak intensity was also significantly higher than that of single-doped Eu3+. The energy transfer phenomenon between Sm3+ and Eu3+ was discovered by the excitation and emission spectra in CYMO:Eu3+,Sm3+ phosphors, and verified by the fluorescence lifetime of Sm3+ ions in the phosphors. The energy transfer mechanism between Sm3+ and Eu3+ is a dipole-dipole interaction, where the energy transfer efficiency in CYMO phosphor doped with 13% Eu3+ and 3% Sm3+ 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% Eu3+,3%Sm3+ phosphor is a red phosphor with excellent performance for potential application in n-UV light excited w-LEDs.