Study on the color tunability and energy transfer mechanism in Tb3+, Sm3+ co-doped CaMoO4 phosphors

Abstract

Tb3+, Sm3+ co-doped CaMoO4 phosphors have been synthesized by chemical precipitation method. The crystal structure and morphology of samples were characterized and analyzed by the X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM). Photoluminescence properties of CaMoO4:Tb3+, Sm3+ and energy transfer from Tb3+ to Sm3+ have been studied in detail. It was found the emitting color of the phosphors could be tuned between green and red by changing the doping concentration of Tb3+/Sm3+, and the color also changed with different excitation wavelength under the same concentration. The average fluorescent lifetime of Tb3+ at 5D4 energy level, energy transfer efficiency and rate from Tb3+ to Sm3+ in CaMoO4 host were calculated. The energy transfer mechanism between Tb3+ and Sm3+ was confirmed to be electric dipole-dipole interaction.