Glass composition dependence of Eu3+ ion red fluorescence

Eu3+ ion-doped B2O3-, SiO2-, and P2O5-based glasses were prepared by the melt-quenching method, and their absorption, fluorescence, and excitation spectra were recorded and assigned. The glass composition dependence of the fluorescence was investigated to obtain the high brightness of the red fluorescence due to the 5D0→7F2 transition of the Eu3+ ion. The integrated intensity of the red fluorescence was the strongest at the Eu2O3 concentration of 3.5 mol% because the cross-relaxation (CR) processes, (5L6→5DJ′)→(7FJ*←7FJ#) and (5DJ→5DJ′)→(7FJ*←7FJ#) (3≧J>J′≧0, 6≧J*>J#≧0) between the Eu3+ ions were promoted, but the CR processes, (5D0→7FJ′)→∑m(7FJ*←7FJ″)m (6≧J′≧0, 6≧J*>J″≧0), between the excited Eu3+ ion at the 5D0 level and m ions of Eu3+ in the 7FJ″ levels were depressed. The former CR processes, (5L6→5DJ′)→(7FJ*←7FJ#) and (5DJ→5DJ′)→(7FJ*←7FJ#) were enhanced in the host glasses consisted of the cations with small ionic radius. In this study, a 70B2O3-30CaO-3.5Eu2O3 glass showed the strongest red fluorescence.