Blue emitting BaMgAl 10O 17:Eu with a blue body color

Abstract

The optical properties of Co 2+-doped BaMgAl 10O 17 (BAM) and BaMgAl 10O 17:Eu (BAM:Eu) are elucidated with emphasis on reflection, (V)UV excitation and luminescence spectra. Doping of BAM with Co 2+ yields a powder with a blue body color equal to that of CoAl 2O 4. Co 2+ is incorporated into the spinel blocks of BAM, which are spaced by Ba–O layers hosting the activator Eu 2+. By means of reflection spectra it is shown that the local environment of Co 2+ is equal to that in CoAl 2O 4, which is responsible for the identical body color. The intrinsic pigmentation of BAM:Eu by Co 2+ 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 Eu 2+. Moreover, the presence of Co 2+ in the host lattice of BAM results in resonant afterglow behavior. Only under photoexcitation at the band gap of BAM:Eu afterglow is observed.