Structure and Luminescent Characteristics of Y1−xEuxNbO4 (x = 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4) Ceramic Solid Solutions

This study focuses on Y1−x EuxNbO4 (x = 0.01–0.40) ceramic solid solutions. The precursor powders were obtained via a liquid-phase route, and the final ceramics were fabricated using conventional ceramic processing (conventional sintering). Using full-profile X-ray diffraction analysis of polycrystals, the phase composition was determined and the structural parameters of solid solution phases were refined as a function of Eu concentration. The morphological features of the microstructure of Y1−xEuxNbO4 ceramics were studied. The visible photoluminescence of Y1−xEuxNbO4 was systematically characterized. The emission spectra for all compositions are dominated by electric dipole 5D0 → 7F2 transition of Eu3+, peaking at ~613 nm. The effects of excitation wavelength (λex = 275, 392, 463, and 535 nm) and Eu content on the efficiency of energy transfer were examined. It was revealed that the concentration quenching of photoluminescence depended on the excitation energy, and at x > 0.2 multipole energy transfer between Eu3+ cations dominated due to the critical distances RC for Y0.8Eu0.2NbO4 was 8.9 Å.