Synthesis and photoluminescence of Eu3+ and Mn2+ doped double phosphates KMLa(PO4)2 (M = Zn, Mg)

Two compounds, KMgLa(PO4)2 and KZnLa(PO4)2 doped with Eu3+ and Mn2+ ions, have been synthesized by a conventional solid-state method at 850 °C. Structures of KMgLa(PO4)2 and KZnLa(PO4)2 have been investigated and confirmed by X-ray diffraction and photoluminescence spectra. The results indicate that the compounds have remained the monoclinic structure of LaPO4 with space group of Cs when (K+, Mg2+) or (K+, Zn2+) could substitute half of the La3+ ions. Under an ultraviolet source, KMgLa(PO4)2:Mn2+ has shown a bright red phosphorescent color, while KZnLa(PO4)2:Mn2+ has shown an orange–red emission which is assigned to the electronic transition of 4T1(4G)–6A1(6S) of Mn2+ in strong crystal field.