Energy transfer and color tunable emission in Tb3+,Eu3+ co-doped Sr3LaNa(PO4)3F phosphors.

A group of color tunable Sr3LaNa(PO4)3F:Tb3+,Eu3+ phosphors were prepared by conventional high temperature solid state method. The phase structures, luminescence properties, fluorescence lifetimes and energy transfer were investigated in detail. Under 369nm excitation, owing to efficient energy transfer of Tb3+→Eu3+, the emission spectra both have green emission of Tb3+ and red emission of Eu3+. An efficient energy transfer occur in Tb3+, Eu3+ co-doped Sr3LaNa(PO4)3F phosphors. The most possible mechanism of energy transfer is dipole-dipole interaction by Dexter's theoretical model. The energy transfer of Tb3+ and Eu3+ was confirmed by the variations of emission and excitation spectra and Tb3+/Eu3+ decay lifetimes in Sr3LaNa(PO4)3F:Tb3+,Eu3+. The color tone can tuned from yellowish-green through yellow and eventually to reddish-orange with fixed Tb3+ content by changing Eu3+ concentrations. The results show that the prepared Tb3+, Eu3+ co-doped color tunable Sr3LaNa(PO4)3F phosphor can be used for white LED.