Crystallographic and optical properties of Li_1−xTa_1−xEu_2xO₃ solid solutions

Abstract

The effects of europium substitution on crystalline solubility, structural changes and optical properties of Li_1−xTa_1−xEu_2xO₃ solid solutions are reported. The solid solutions exist over a very limited range of europium concentrations (x ≤ 0.02). They were characterized by X-ray powder diffraction and density measurements. The liquid nitrogen fluorescence and excitation spectra of Eu³⁺ in the solid solutions were measured in the frequency range 12,200–45,450 cm⁻¹. The emission mainly arises from the ⁵ D ₀ level to Stark components of the five lowest ⁷ F _j (j = 0, 1, 2, 3, 4) states. It was inferred from the analyses of the optical and density data that the Eu³⁺ ions may lie on both Li and Ta sites, but not on the intrinsic vacant lattice sites.

Key Words:

• Solid solutions
• lithium metatantalate
• optical properties