Crystal structure of Eu-doped magnetoplumbite-type lanthanum aluminum oxynitride with emission site splitting

Eu-doped lanthanum aluminum oxynitride (LaAl12(O,N)19) with magnetoplumbite structure was prepared by nitridation of the oxide precursor obtained from aluminum glycine gel and subsequent post-annealing. Eu-doped lanthanum aluminum oxynitride exhibited blue light emission at 440 nm with a shoulder at 464 nm under excitation at 254 nm. Isostructural Eu-doped calcium aluminum oxide (CaAl12O19) exhibited a single emission peak at 415 nm. Structural refinement using neutron powder diffraction indicated that the lanthanum site occupied partially by Eu2+ splits into 2d and 6h sites in the aluminum oxynitride. The longer emission and the shoulder peak in the former aluminum oxynitride were observed in relation to the increasing covalency as well as crystal field splitting around doped Eu2+ induced by site splitting involved with the two kinds of anions.

Graphical AbstractMagnetoplumbite type Eu-doped lanthanum aluminum oxynitride has lanthanum site splitting induced by two kinds of anions, causing two emission peaks.Figure optionsDownload as PowerPoint slideHighlights
► Magnetoplumbite type LaAl12(O,N)19 doped with Eu shows emission peak splitting.
► ND analysis is performed on La0.97Eu0.03Al12(O,N)19 and Ca0.97Eu0.03Al12O19.
► La0.97Eu0.03Al12(O,N)19 has lanthanum site splitting.
► The lanthanum site splitting is induced by coexisting of two kinds of anions.