Synthesis and Luminescence Properties of ZrO2 and ZrO2/SiO2 Composites Incorporating Eu(III)-Phenanthroline Complex Prepared by a Catalyst-Free Sol-Gel Process

Class I organic–inorganic hybrid materials consisting of zirconia and zirconia/silica matrices doped with europium(III)–1,10-phenanthroline complex were prepared by a catalyst-free sol–gel route. Two different experimental procedures were developed to incorporate the coordination compound into the matrix in order to study the possible influence of the preparation method on the optical properties of the rare earth ion. Besides, the effects of the annealing temperature and the composition of the matrix were investigated. Infrared spectra, Eu(III) luminescence lifetimes, relative emission intensities, excitation and emission spectra are reported. The products yielded under UV excitation strong red emission similar to the one of the neat coordination compound. The relative emission intensities and lifetimes show a maxima when determined as a function of annealing temperature, preparation procedure and matrix composition.