Luminescent properties and energy transfer mechanism of NaGd(MoO4)2:Sm3+, Eu3+ phosphors

Sm3+ singly doped NaGd(MoO4)2 and Sm3+, Eu3+ co-doped NaGd(MoO4)2 phosphors by using sodium citrate as chelating agent were synthesized via hydrothermal method. The structure and morphology were characterized by means of X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). During the synthesis process, the Na3Cit concentration plays a crucial role in determining the morphology and particle size of the products. The optimal doping concentration in Sm3+ singly doped NaGd(MoO4)2 phosphor was confirmed. The relevant parameters of energy transfer in the NaGd(MoO4)2: Sm3+, Eu3+ phosphors have been calculated based on the fluorescent dynamic analysis. Finally, on the analysis of luminescent spectra and fluorescent dynamics, the main energy transfer mechanism between Sm3+ and Eu3+ in NaGd(MoO4)2 phosphor is confirmed to be electric dipole-dipole interaction, and energy transfer pathway is from 4G5/2 state of Sm3+ to 5D0 state of Eu3+ rather than 5D1 of Eu3+ ions.