Host-lattice emission, energy transfer and degradation processes are characterized in undoped and Eu-doped BaMgAl 1 0 O 1 7 . Undoped BaMgAl 1 0 O 1 7 exhibits a broad emission centered at 265nm when excited at wavelengths shorter than 190nm. This emission is assigned to exciton recombination at Ba-O groups in the cation layer of the lattice. The emission exhibits excellent overlap with the excitation band of Eu 2 + in this host, providing a means of host-to-activator energy transfer in the doped phosphor. The exciton emission is relatively stable to thermal damage, but undergoes a peak shift and significant decrease in intensity after exposure to VUV radiation. Heating of VUV-damaged materials in air leads to some repair of the spectral properties.