LUMINESCENCE PROPERTIES OF RARE-EARTH (EU3-PHENANTHROLINE INCORPORATED INTO A SILICA MATRIX BY SOL-GEL METHOD( AND TB3+) COMPLEXES WITH PARAAMINOBENZOIC ACID AND 1,10)

Ternary complexes of europium and terbium with paraaminobenzoic acid a nd 1,10-phenanthroline (Eu(p-ABA)(3). phen . 2H(2)O and Tb(p-ABA)(3). phen . 2H(2)O, where p-HABA = paraaminobenzoic acid and phen = 1,10-ph enanthroline) 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 o f emission, excitation spectra, and Lifetimes. Within the range of eff ective dopant concentrations, the luminescence intensities of rare-ear th complexes in silica gel increase with the increasing of their dopan t concentration. The lifetimes of rare-earth ions (Eu3+ and-Tb3+) in s ilica gel doped with europium and terbium complexes become longer than those in pure complexes. Very small amounts of rare-earth complexes d oped in silica gel matrix can exhibit excellent luminescence propertie s, (C) 1998 Elsevier Science Ltd.