Photoluminescence properties and local electronic structures of rare earth-activated Sr 3AlO 4F

Abstract

Photoluminescence properties and local electronic structures of rare earth (Eu 3+ and Ce 3+) activated Sr 3AlO 4F have been studied. X-ray powder diffraction data indicated that the activator ions of Eu 3+ and Ce 3+ can be incorporated into the Sr 3AlO 4F lattice and formed limited solid solutions of Sr 3−2 x Ln x Na x AlO 4F (Ln = Eu, Ce) with Na + as a charge compensator ion. The local structure around Sr sites was initially explored using Eu-activated Sr 3AlO 4F as a structural probe. Sr 3AlO 4F:Eu 3+ exhibits orange-red emission ranging from 520 to 740 nm with a maximum peak at about 619 nm mainly originating from the 5D 0 → 7F J ( J = 0, 1, 2, 3, 4) transitions, indicating that Eu exists mainly in the trivalent state due to a strong oxidative lattice in Sr 3AlO 4F. Sr 3AlO 4F:Ce 3+ shows an unusual long-wavelength 4f → 5d excitation band of Ce 3+ at about 405 nm due to a large crystal field splitting of the 5d levels of Ce 3+ in relation to its crystal structure. Under near-UV excitation in the range of 375–405 nm, Sr 3AlO 4F:Ce 3+ exhibits efficient blue-green emission at about 506 nm. Given high absorption and efficient excitation in the near-UV region, Sr 3AlO 4F:Ce 3+ demonstrates a potential blue-green emitting phosphor for applications in white LED lighting.