Crystal structure, energy transfer and tunable luminescence of Ca8(Mg,Zn)Ce(PO4)7:Eu2+ solid solution phosphor

Abstract

Here we investigated the tunable luminescence properties of Ca8(Mg1−xZnx)Ce(PO4)7:Eu2+ as a function of Zn2+ concentration. All the synthesized phosphors shared the same whitlockite-type structure and crystallized in the rhombohedral unit cell with the space group R3c (no.161). Energy can be efficiently transferred from Ce3+ to Eu2+ in Ca8(Mg1−xZnx)Ce(PO4)7:Eu2+ phosphors. Furthermore, the color of these phosphors can turn from blue to green with increasing the Zn content (x). Such tunable luminescence cannot be attributed to the effect of crystal field splitting or energy transfer between Ce3+ and Eu2+ ions. It is found that the modification of host composition via Zn substitution causes different Eu2+ sensitization efficiencies and induces the luminescence tuning. This mechanism may be general in iso-structural solid-solution phosphors and will be useful in tuning optical and other properties whose sensitization efficiency is sensitive to the host composition.