Investigation of energy transfer mechanism and luminescence properties in Eu3+ and Sm3+ co-doped ZnWO4 phosphors

A series of ZnWO4:x%Eu3+, y%Sm3+ phosphors were synthesized by a facile hydrothermal method. The samples were well crystallized in the pure monoclinic wolframite structure with P2/c space group. The produced phosphors have exhibited an intense red emission, moreover, the red emission intensity was enhanced gradually with the increase of the Sm3+ content. The energy transfer (ET) of Sm3+→Eu3+ was proved by the photoluminescence (PL) spectra and decay curves. The average lifetime of Eu3+ emission was also decreased from 1.11 ms in ZnWO4:5%Eu3+ to 0.90 ms in ZnWO4:5%Eu3+, 2%Sm3+, which demonstrates that there exists ET from Sm3+ to Eu3+. These results show that the samarium ions doping greatly enhances the emission dominance of Eu3+ at 617 nm.