Enhancement of phosphor efficiency via composition modification

Abstract

The luminescence efficiency of ${\mathrm{Mn}}^{4+}$-doped $\mathrm{Ca}{\mathrm{Al}}_{12}{\mathrm{O}}_{19}$ (Mn:CAO) is significantly improved by composition modification. The leading mechanism that quenches the ${\mathrm{Mn}}^{4+}$ photoluminescence is the formation of ${\mathrm{Mn}}^{4+}$ pairs in the lattice of $\mathrm{Ca}{\mathrm{Al}}_{12}{\mathrm{O}}_{19}$ (CAO) with interstitial ${\mathrm{O}}^{2-}$ for charge compensation. Mixing ${\mathrm{Mg}}^{2+}$ ions into the CAO lattice may form ${\mathrm{Mn}}^{4+}–{\mathrm{Mg}}^{2+}$ pairs and reduce the number of ${\mathrm{Mn}}^{4+}$ pairs, thus enhancing the ${\mathrm{Mn}}^{4+}$ luminescence efficiency by more than three times. It is shown that the presence of ${\mathrm{Mg}}^{2+}$ leads to formation of additional phases that also affect the optical properties of ${\mathrm{Mn}}^{4+}$.

© 2008 Optical Society of America

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