Tunable luminescence and energy transfer in Eu3+ doped Ca8MTb(PO4)7 (M = Mg, Zn, Ca) phosphors

Abstract A series of Ca8MTb1–xEux(PO4)7 (M = Mg2+, Zn2+, Ca2+; 0 ≤ x ≤ 1) with β-Ca3(PO4)2-type structure have been synthesized via a standard solid-state method. X-ray diffraction, second harmonic generation, photoluminescence emission and excitation spectra, and decay time curves were used to characterize solid solutions. The color coordinates of as-prepared samples can be shifted from green to red regions by the increasing of Eu3+ concentration. Red-to-orange (R/O) and green-to-blue (G/B) factors indicate a higher local symmetry of emitting Eu3+ and Tb3+ ions environment in Ca8MTb1–xEux(PO4)7 (M = Mg, Zn) in comparison to Ca9Tb1–xEux(PO4)7. The study shows that Zn-incorporation in the β-Ca3(PO4)2 matrix increases the luminescence intensity by 15%. The presented results indicate that the synthesized solid solutions can be considered as new single-phase phosphors.