Small Thermal Quenching, Narrow Green Emitting γ-AlON: Ce3+, Mn2+ Phosphor: Luminescence and Energy Transfer

A series of γ-AlON: Ce3+, Mn2+ phosphors were prepared via a high-temperature solid-state reaction. The phase formation and morphology, photoluminescence excitation and emission spectra, absorption spectra, lifetime, and thermal stability were investigated in detail. The γ-AlON: Ce3+, Mn2+ phosphor showed two emission bands under 285 nm excitation. The first broad band at 400 nm was attributed to Ce3+ ion emission, and the narrow band found at 517 nm was assigned to the Mn2+ ions. The critical distance of energy transfer from Ce3+ to Mn2+ has been calculated according to the concentration quenching method. The mechanism of energy transfer from Ce3+ to Mn2+ was of the resonance type and occurred via a dipole − dipole interaction. After doping Ce3+ in the γ-AlON matrix, the absorption, internal quantum, and external quantum efficiencies of γ-AlON: Ce3+, Mn2+ can be increased to 68.8%, 60.9%, and 41.9%, respectively. Furthermore, γ-AlON: Ce3+, Mn2+ exhibited superior thermal stability, with the emission intensity measured at 150°C maintaining 99% of the maximum emission intensity.