Preparation, electronic structure and optical properties of CoxLaMg1−xAl11O19 microcrystals

Co-doped LaMgAl 11 O 19 microcrystals were synthesized by a facile sol–gel method. The as-synthesized microcrystals were near hexagonal sheets in shape with the diameter of 100–250 nm and the thickness of 30–50 nm. The electronic structure of the samples was studied using X-ray photoelectron spectroscopy. Co 2+ ions are mainly located in tetrahedral sites in the samples, and the binding energy value of Co 2p 3/2 decreased with increasing cobalt content. The ionicity of Al–O bond slightly enhanced at first and then kept unchanged with the increase of cobalt content. The absorption and luminescence properties were also studied. All samples exhibited strong absorption band near 600 nm, which was characteristics of tetrahedral Co 2+ ions. The weak absorption band at about 350 nm indicated the presence of small amount of octahedral Co 2+ . The results of XPS and absorption spectra indicated that the fraction of octahedral Co 2+ slightly increased with increasing cobalt concentration. The intense emission at 695 nm was observed for Co 0.01 LaMg 0.99 Al 11 O 19 sample, Co-doped LaMgAl 11 O 19 microcrystals show promising application as phosphors. This study also provides a facile method to prepare other microcrystals materials.