Luminescence properties of rare-earth (Eu3+ and Tb3+) complexes with paraaminobenzoic acid and 1,10-phenanthroline incorporated into a silica matrix by sol-gel method

Ternary complexes of europium and terbium with paraaminobenzoic acid and 1,10-phenanthroline (Eu(p-ABA)3·phen·2H2O and Tb(p-ABA)3·phen·2H2O, where p-HABA = paraaminobenzoic acid and phen = 1,10-phenanthroline) were introduced into a silica matrix by sol-gel method. The luminescence behavior of the complexes in silica gels was studied in comparison with the corresponding solid-state complexes by means of emission, excitation spectra, and lifetimes. Within the range of effective dopant concentrations, the luminescence intensities of rare-earth complexes in silica gel increase with the increasing of their dopant concentration. The lifetimes of rare-earth ions (Eu3+ and Tb3+) in silica gel doped with europium and terbium complexes become longer than those in pure complexes. Very small amounts of rare-earth complexes doped in silica gel matrix can exhibit excellent luminescence properties.