Luminescence, energy transfer, color tunable properties of Ca9ZnK(PO4)7: Ce3+/Tb3+/Mn2+ phosphor

A series of violet-green-red color-tunable Ca9ZnK(PO4)7: Ce3+/Tb3+/Mn2+ phosphors were synthesized via high temperature solid-state method. The luminescence properties, energy transfer and thermal stability were investigated in detail. When doped with trivalent cerium, Ca9ZnK(PO4)7: Ce3+ presents strong violet luminescence under UV excitation. Incorporating Tb3+ and Mn2+ into Ca9ZnK(PO4)7: Ce3+ generates enhanced Tb3+ green emission peak and Mn2+ red emission band. The Ce3+ sensitization effect on Tb3+ and Mn2+ is verified by the variation of PL/PLE spectra, Ce3+ decay lifetimes and energy transfer efficiency of Ca9ZnK(PO4)7: Ce3+, Tb3+/Mn2+ phosphors. The color tone can be tuned from violet (0.196, 0.102) to green (0.343, 0.563) and to red (0.676, 0.311) by properly changing the ratio of Ce3+/Tb3+ and Ce3+/Mn2+. The representative Ca9ZnK(PO4)7: 0.01Ce3+, 0.07Tb3+ sample shows good thermal stability with 95% of its room temperature PL intensity at 180 °C. These results indicate that Ca9ZnK(PO4)7: Ce3+/Tb3+/Mn2+ may be potential candidates as single-phase color-tunable phosphors for UV-convertible devices.