Crystal structure and near-ultraviolet photoluminescence properties of Ba9Sc2Si6O24:Ce3+,Na+

Ce3+-doped Ba9Sc2Si6O24 phosphors with a charge-compensating ion Na+ were prepared by solid-state reaction. The crystal structures of the samples with different Ce3+ concentration were investigated, as well as photoluminescence properties in the near ultraviolet–visible range. From the low temperature excitation and emission spectra of samples with low and high Ce3+ concentrations, we found that Ba2+ ions in three different crystallographic sites were replaced by Ce3+ ions in the host, while two of them were very similar. Accordingly, there are two types of luminescent centers in BSSO:Ce3+ i.e. Ce3+(1) in the Ba(1) site and Ce3+(2) in the Ba(2) and Ba(3) sites. With the increase of Ce3+ concentration, the emission intensity from Ce3+(1) becomes lower compared with that of Ce3+(2) due to the energy transfer between these two centers, which were confirmed by the life-time and low temperature test results.