Tunable luminescence and energy transfer properties of a novel Na4Ca4Si6O18:Ce3+,Mn2+ phosphor

A series of color-tunable Na4Ca4Si6O18: Ce3+, Mn2+ phosphors were synthesized via a high-temperature solid-state reaction. The effect of Ce3+ concentration on the emission intensity of Na4Ca4Si6O18: Ce3+ is studied, and the energy transfer from Ce3+ to Mn2+ is observed. The emission spectra of the Na4Ca4Si6O18: Ce3+, Mn2+ phosphors show a blue band at 430 nm of Ce3+ and a red band at 590 nm of Mn2+, originating from the allowed 5d -> 4f transition of the Ce3+ ion and the T-4(1g)(4G) -> (6)A(1g)(6S) transition of the Mn2+ ion, respectively. Non-radiative transitions between the Ce3+ and Mn2+ ions in the Na4Ca4Si6O18 host are demonstrated to be dipole-quadrupole interactions. Results indicate that the varied emitted color from blue to red can be achieved by tuning the relative ratio of the Ce3+ to Mn2+ ions based on the principle of energy transfer. We have demonstrated that Na4Ca4Si6O18: Ce3+, Mn2+ phosphors can be promising candidates for color-tunable phosphors applied in near-UV white LEDs.