Improved optical photoluminescence by charge compensation and luminescence tuning in Ca6Ba(PO4)4O:Ce3+, Eu2+ phosphors

We comparatively investigated the effect of different charge compensators (Li+, Na+, K+ and Si4+) via the charge balance strategies of (i) 2Ca(2+) -> Ce3+ + M+ (M = Li, Na, K) and (ii) Ca2+ + P5+ -> Ce3+ + Si4+ on the photoluminescence (PL) properties of blue-emitting Ca6Ba.PO4)(4)O:Ce3+ phosphors. The optimized emission intensity was realized in Ca6Ba.PO4)(4)O:Ce3+ with codoping Li+. The different charge compensation mechanisms and PL enhancement were analysed. Moreover, tunable luminescence can be further achieved through the introduction of Eu2+ into the Ca6Ba.PO4)(4)O:Ce3+, Li+ phosphor, and charge compensation also plays an important role in the optimization of luminescence behaviours. It is proved that the emission spectra of Ca6Ba.PO4)(4)O:Ce3+, Li+, Eu2+ can be tuned from 463 to 528 nm through Ce3+-Eu2+ energy transfer (ET). The intrinsic ET mechanism and process have also been studied.