The effect of charge compensation by means of Na+ ions on the luminescence behavior of Sm3+-doped CaAl4O7 phosphor

► Sm3+ doped CaAl4O7 exhibits intense orange-red emission when excited at 404.5 nm. ► In CaAl4O7:Sm3+ sample the active ions occupy more than on symmetry center. ► Co-doping with Na+ ions leads to one emission center and strongly enhanced Sm3+ luminescence. ► Cross-relaxation process is enhanced in the case of single Sm3+ doped samples.