Blue emitting BaMgAl10O17:Eu with a blue body color

The optical properties of Co2+-doped BaMgAl10O17 (BAM) and BaMgAl10O17:Eu (BAM:Eu) are elucidated with emphasis on reflection, (V)UV excitation and luminescence spectra. Doping of BAM with Co2+ yields a powder with a blue body color equal to that of CoAl2O4. Co2+ is incorporated into the spinel blocks of BAM, which are spaced by Ba-O layers hosting the activator Eu2+. By means of reflection spectra it is shown that the local environment of Co2+ is equal to that in CoAl2O4, which is responsible for the identical body color. The intrinsic pigmentation of BAM:Eu by Co2+ yields a phosphor with an improved color point due to the self-absorption of the low-energy tail of the 4f-5d emission band of Eu2+. Moreover, the presence of Co2+ in the host lattice of BAM results in resonant afterglow behavior. Only under photoexcitation at the band gap of BAM:Eu afterglow is observed. (C) 2003 Elsevier Science B.V. All rights reserved.