Photoluminescent and Magnetic Properties of Lanthanide Containing Apatites: NaxLn10–x(SiO4)6O2–yFy, CaxLn10–x(SiO4)6O2–yFy (Ln = Eu, Gd, and Sm), Gd9.34(SiO4)6O2, and K1.32Pr8.68(SiO4)6O1.36F0.64

Single crystals of NaEu9(SiO4)6O2, Na1.5Eu8.5(SiO4)6OF, Na1.64Gd8.36(SiO4)6O0.72F1.28, Gd9.34(SiO4)6O2, Ca2.6Eu7.4(SiO4)6O1.4F0.6, Ca4.02Sm5.98(SiO4)6F2, and K1.32Pr8.68(SiO4)6O1.36F0.64 and powders of NaEu9(SiO4)6O2, Na1.5Eu8.5(SiO4)6OF, Eu9.34(SiO4)6O2, and Gd9.34(SiO4)6O2 were synthesized via flux growth in selected alkali-fluoride melts. All of the compounds adopt the apatite structure with space group P63/m. Luminescence and magnetic data were collected on NaEu9(SiO4)6O2, Na1.5Eu8.5(SiO4)6OF, Eu9.34(SiO4)6O2, and Gd9.34(SiO4)6O2. Luminescent data indicate that changing the cations and anions that surround the lanthanide site does not change the luminescent properties, making apatites versatile structures for optical materials.