Tuning of the emission wavelength for AlN:Eu2+, Ca2+ phosphors prepared by freeze drying assisted combustion synthesis

AlN based phosphors have a wide range of applications and the green and blue emission of AlN:Eu 2+ phosphors have been reported a lot, while we found yellow emission in this phosphor. In this work, a series of different concentrations of Ca 2+ -doped AlN:Eu 2+ phosphors have been successfully prepared by a freeze drying assisted combustion synthesis, of which the crystal structure, morphology, photoluminescence properties and luminescence mechanism were studied in detail. The results show that Ca 2+ ions have been successfully doped into the AlN:Eu 2+ lattice and cause the lattice distortion, which has a great influence on the luminescent properties of the phosphors. Under the 365 nm excitation, the phosphors present a single emission peak, which is ascribed to the 4f 6 5d-4f 7 transitions of Eu 2+ ions. Furthermore, by increasing the doping amount of Ca 2+ ions (0.1, 0.5, 1 and 3 at %), the emission wavelength can be tuned from 516 to 535 nm, corresponding to the emission color from green to yellow, which is owing to the enhancement of the crystal field intensity around Eu 2+ ions through the interaction between Ca 2+ and Eu 2+ ions. Tuning of the emission wavelength for AlN:Eu 2+ phosphors is of great importance in expanding the applications of AlN:Eu 2+ phosphors in various luminescent fields.