Color Tuning Luminescence of Ce³⁺/Mn²⁺/Tb³⁺-Triactivated Mg₂Y₈(SiO₄)₆O₂ via Energy Transfer: Potential Single-Phase White-Light-Emitting Phosphors

Ce 3+, Mn 2+, and Tb 3+ -activated Mg 2 Y 8 (SiO 4 ) 6 O 2 (MYS) oxyapatite phosphors have been prepared via solid state reaction process. The Ce 3+ emission at different lattice sites in MYS host has been identified and discussed. Under UV excitation, there exist dual energy transfers (ET), that is, Ce 3+ → Mn 2+ and Ce 3+ → Tb 3+ in the MYS: Ce 3+ /Mn 2+ /Tb 3+ system. The energy transfer from Ce 3+ to Mn 2+ in MYS: Ce 3+ /Mn 2+ phosphors has been demonstrated to be a resonant type via a dipole–quadrupole mechanism, and the critical distance ( R C ) calculated by quenching concentration method and spectral overlap method are 10.5 and 9.7 Å, respectively. The emitting colors of MYS: Ce 3+ /Mn 2+ /Tb 3+ samples can be adjusted from blue to orange-red via ET of Ce 3+ → Mn 2+ and from blue to green via ET of Ce 3+ → Tb 3+, respectively. More importantly, a wide-range-tunable white light emission with high quantum yields (37–47%) were obtained by precise control of the contents of Ce 3+, Mn 2+, and Tb 3+ ions. On the other hand, the CL properties of MYS: Ce 3+ /Mn 2+ /Tb 3+ phosphors have been investigated in detail. The results indicate that the as-prepared MYS: Ce 3+ /Mn 2+ /Tb 3+ phosphors have good CL intensity and CIE coordinate stability with a color-tunable emission crossing the whole visible light region under low-voltage electron beam excitation. In conclusion, the white light with varied hues has been obtained in Ce 3+, Mn 2+ and Tb 3+ -activated MYS phosphors by utilizing the principle of energy transfer and properly designed activator contents as well as the select of excitation wavelength under UV and low-voltage electron beam excitation.