Energy Transfer Mechanism of KAlSiO4 : Re3+ (Re = Dy/Sm) Phosphors

A series of Dy3+, Sm3+ co-doped KAlSiO4 phosphor materials were prepared by the high temperature solid phase method. The experimental results show that the doping of a small amount of Dy3+ and Sm3+ does not change the crystal structure of KAlSiO4. When KAlSiO4 1% Dy3+, woo Sm3+ is excited at the characteristic excitation wavelength of Dy3+, there occurs a resonant non-radiative energy transfer from Dy3+ to Sm3+ in samples. Meanwhile, the color coordinate shift is very small and there exists a red shift at 528 nm and a blue shift at 713 nm. In contrast, when KAlSiO4 1.50 Sm3+, Dy3+ is excited at the characteristic excitation wavelength of Sm3+ the emission spectrum is very similar to that of KAlSiO4 1. 5% Sm3+ and there are no characteristic emission peaks of Dy3+. However, the luminous intensity of Sm3+ at 651 nm is increased by 6.5 times, which indicates that there does not exist energy return from Sm3+ to Dy3+ and the doping of Dy3+ promotes crystal lattice matching and greatly enhances the luminous intensity of Sm3+. Theoretical calculations show that the maximum energy transfer efficiency from Dy3+ to Sm3+ reaches up to 52% and the energy transfer interaction is electric quadrupole-quadrupole interaction. The color coordinates of phosphors are all around (0.41, 0. 51) and located in the yellow-green area. The internal quantum yield under 386 nm excitation gradually increases from 25. 8 0% to 42. 6 %.