Co-fluorescence effect of rare earth complexes with 4-aminobenzoic acid in a silica matrix

Terbium(III), yttrium(III), and neodymium(III) complexes with 4-aminobenzoic acid have been co-doped into silica matrix. For the samples, the characteristic emissions of terbium(III) increase obviously with the addition of yttrium(III) complex, while the reverse is true with the addition of neodymium(III) complex. Compared with terbium(III) complex doped silica sample, the photoacoustic signal of the ligand decreases for terbium(III)–yttrium(III) complexes co-doped sample, and increases for terbium(III)-neodymium(III) complexes co-doped sample. The fluorescence quantum yields and lifetimes of the samples have been determined. The co-fluorescence mechanism has been discussed from radiative and nonradiative relaxations. The nephelauxetic parameters and photoacoustic branching vectors of neodymium(III) in the silica samples have also been calculated. The spectral result indicates that heteronuclear complexes may form in the silica matrix upon a suitable heat treatment. The co-fluorescence effect found in the inorganic matrix can contribute to the better design and application of rare earths containing fluorescent materials.