Influence of crystal structure on the luminescence properties of bismuth(III), europium(III) and dysprosium(III) in Y2SiO5

Abstract

The luminescence properties of Bi³⁺, Eu³⁺, Dy³⁺ and energy transfer from Bi³⁺ to Dy³⁺ and Eu³⁺ have been studied in two modifications of Y₂SiO₅(low-temperature X₁ type and high-temperature X₂ type) and discussed in relation to their crystal structures. The Bi³⁺ ion luminesces in the blue region of the spectrum in X₁-Y₂SiO₅ but in the UV region in X₂-Y₂SiO₅. Two obviously different luminescent centres have been observed for Bi³⁺ and Eu³⁺ in X₁-Y₂SiO₅, but only one has been seen in X₂-Y₂SiO₅. The Stokes shift (9200 cm^–1) for Bi³⁺ in X₁-Y₂SiO₅ is much larger than that (5000 cm^–1) in X₂-Y₂SiO₅. This suggests that the host lattice is more rigid in X₂-Y₂SiO₅ than in X₁-Y₂SiO₅. As a result, the Bi³⁺, Eu³⁺ ions show higher emission intensity in the former than in the latter type. X₁-Y₂SiO₅ is more suitable for Bi³⁺→ Eu³⁺ energy transfer and X₂-Y₂SiO₅ is more suitable for Bi³⁺→ Dy³⁺ energy transfer.