Préparation,sites de symétrie et photoluminescence de l'ion Bi3+ dans les antimoniates de terres rares Y2BSbO7 (B = Ga,Lu, Y)

New rare-earth antimonates Y₂BSbO₇(B = Ga, Lu, Y) have been prepared. Excitation and emission spectra of these host lattices doped with Eu³⁺ reveal two symmetry sites for Eu³⁺ (Y and B sites). The symmetry of these sites is not D_3d as in the pyrochlore structure.The photoluminescence of the Bi³⁺ ion is analysed in these compounds. The spectra are ascribed to the ³¹S₀ → ³P₁ and ³P₁ → ¹S₀ transitions with a perturbation due to the ³P₀ metastable level. The decay curve consists of two exponentials in agreement with the presence of Bi³⁺ in two symmetry sites.