Single-phase ceramic samples of silicate apatites M2Ln8(SiO4)6O2 (M = Mg, Ca, Sr; Ln = Y, La) undoped and doped with Eu3+, Ce3+, or Mn2+ ions were obtained by the high-temperature solid-state reaction technique using precursors synthesized under hydrothermal conditions. The phosphors were characterized by XRD analysis, Raman spectroscopy, and steady-state/time-resolved and site-selective photoluminescence spectroscopy under blue-to-VUV excitation. It is shown that the small-radius Mg2+ ions, which can occupy two types of suitable sites in the apatite structure, strongly influence luminescence properties of apatites, in particular the distribution of Eu3+ ions between these sites. A bright broad-band yellow emission (peaked at 560 nm with t < 1 ms) was obtained from the Mg2La8(SiO4)6O2:Eu apatite after annealing it in a H2(15%)/Ar reducing atmosphere. This emission is due to 5d–4f transitions of Eu2+ and is efficiently excited by near UV-to-blue light (300–450 nm). Silicate apatites co-doped with optimal concentrations of Eu3+/Eu2+ or Eu2+/Mn2+ can be considered as possible single-phase phosphors for application in warm white pc-LEDs.
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