Influence of Mg2+ on luminescence efficiency and charge compensating mechanism in phosphor CaAl12O19:Mn4+

Synthesized by a modified solid state method in air and mixed with MgO, the red phosphor of CaAl12O19:yMn4+ (y=0.001-1.5%) enhanced its photoluminescence efficiency by 3.5 times. The influence of MgO on crystal phases, luminescence intensity and spectral characteristics of the composition modified phosphor has been investigated by spectroscopic experiments and luminescence decay measurements. It is observed that the decay time of Mn4+ luminescence prolongs linearly with increase of MgO in the composition, indicating that the excitation energy transfer and non-radiative relaxation between Mn4+-Mn4+ pairs decrease. The presence of Mg2+ leads to a transformation of Mn4+-Mn4+ pairs connected with interstitial O2- to isolated Mn4+ ions and therefore eliminates energy transfer and provides charge compensation as well. - Research highlights: → Enhancement of phosphor efficiency via composition modification. → Investigation of charge compensation, energy transfer and non-radiative relaxation mechanisms in Mn4+ activated red phosphors. → Demonstration of the role of MgO in elimination of Mn4+-Mn4+ pair formation and luminescence enhancement.