Luminescence of Eu³⁺ in La_1-xEu_xTa₇O₁₉ (0<x≤1) solid solution

The luminescence properties of Eu³⁺ in La_1-xEu_xTa₇O₁₉ solid solution were examined systematically. In the structure the nearest neighbours of La³⁺ sites doped with Eu³⁺ ions are arranged two-dimensionally with proper separations of about 0.62 nm. An intense emission peak is observed at 610 nm together with supplementary weak peaks. All the peaks can be ascribed to ⁵D_j → ⁷F_j′ (j = 0,1; j′=0,1,2,3,4) transitions of Eu³⁺. The emission of the ⁵D₀ → ⁷F₂ transition becomes intense and saturates with the Eu³⁺ concentration. As a result, the profile of the concentration quenching implies that energy migration of excited Eu³⁺ hardly takes place in La_1-xEu_xTa₇O₁₉ solid solution.