Luminescence property, energy transfer and thermal stability of Sr_6Ca_4(PO_4)_6F_2:Ce~(3+), Tb~(3+), Sm~(3+) for white light emitting diodes

摘要

Series of Sr_6Ca_4(PO_4)_6F_2:Ce~(3+), Tb~(3+), Sm~(3+) are prepared by a high temperature solid state method. Ce~(3+), Tb~(3+) or Sm~(3+) single-doped Sr_6Ca_4(PO_4)_6F_2 can produce blue, green and red emission under ultraviolet excitation, respectively. However, the emission intensities of Tb~(3+) and Sm~(3+) are relatively weak due to their forbidden transition. In order to achieve white light, the spectral property and decay curves of Sr_6Ca_4(PO_4)_6F_2:Ce~(3+)/Tb~(3+)/Sm~(3+) are measured, not only the energy transfer of Ce~(3+)-Tb~(3+), Ce~(3+)-Sm~(3+) and Tb~(3+)-Sm~(3+) was demonstrated, importantly, but also the single-phase white emitting phosphor Sr_6Ca_4(PO_4)_6F_2:0.14Ce~(3+), 0.07Tb~(3+),0.13Sm~(3+) was obtained by the energy transfer.