Microstructure of Eu~(3+)-Doped Perovskites-Type Niobate Ceramic La_3Mg_2NbO_9

摘要

Eu~(3+)-doped red-emitting ceramics of Eu~(3+)-doped La_3Mg_2NbO_9 were prepared via typical solid state. X-ray diffraction and scanning electron microscope were utilized to characterize the ceramics. The photoluminescence excitation and emission spectra, the fluorescence decay curves, and color coordinates were investigated. The concentration quenching of the samples were discussed as well. The microstructures of the ceramics were discussed according to the spectral properties of probe ions of Eu~(3+), for example, substitution sites for Eu~(3+), inhomogeneous broadening and splitting of the emission bands, nonexponential decay, ~5D_0→~7F_0 emission transition, distorted symmetry sites, etc. The crystal structure of La_3Mg_2NbO_9 is heavily distorted due to the mixed occupation of Mg and Nb on B sites. Eu~(3+) ions only substitute La sites and Eu~(3+) ions (or rare-earth ions) are arranged in the heavily disordered environments over the whole structure in La_3Mg_2NbO_9.