Defect chemistry and VUV optical properties of the BaMgAl 10O 17:Eu 2+–Ba 0.75Al 11O 17.25:Eu 2+ solid solution

Abstract

The optical properties of the BaMgAl 10O 17:Eu 2+ (BAM)–Ba 0.75Al 11O 17.25:Eu 2+ (BAL) solid solution have been studied using VUV excitation, emission and reflectance spectroscopy. Three unique Eu 2+ emission centers are observed in a ratio that depends on the composition of the host and the dopant concentration. Two of the emission centers are assigned to Eu on normal Beevers–Ross sites and Eu on anti Beevers–Ross sites. The defect chemistry of this system is modeled based on the known behavior of the spinel (MgO· nAl 2O 3) system. Based on this model, the third Eu center can be assigned either to Eu near Al vacancies or to Eu associated with O atoms in the cation layer. In undoped materials exciton emission is observed, peaking at 263 nm in BAM and 285 nm in BAL. This emission may be the mechanism of host-to-activator energy transfer in these phosphors.