Luminescence Properties and Energy Transfer of Eu/Mn-Coactivated Mg2Al4Si5O18 as a Potential Phosphor for White-Light LEDs

A series of blue-to-white emitting Mg2Al4Si5O18: Eu2+, Mn2+ phosphors were synthesized via high-temperature solid-state method, and their luminescence properties were investigated in detail. Under near-ultraviolet (UV) light excitation of 365 nm, Eu2+-doped Mg2Al4Si5O18 exhibits a broad blue emission band peaked at 469 nm, and Mn2+-doped Mg2Al4Si5O18 shows a broad orange-red emission band near 600 nm. The energy transfer from Eu2+ to Mn2+ in Mg2Al4Si5O18 host matrix can be found, and the resonant type is demonstrated by a dipole–quadrupole mechanism. The emission hue can be tuned from blue (0.17, 0.17) to bluish green (0.22, 0.29) and finally to white (0.31, 0.33) by properly varying the ratio of Eu2+/Mn2+. The thermal quenching property of the sample was investigated, and the activation energy ΔE was estimated to be 0.30 eV. Additionally, the energy transfer critical distance between Eu2+ and Mn2+ was calculated. With appropriate tuning of activator content, the Mg2Al4Si5O18: Eu2+, Mn2+ phosphor may have potential application for UV light-emitting diodes.