Electronic structure, optical and thermal/concentration quenching properties of Lu_2−2xEu_2xWO₆ (0 ≤ x ≤0.2)

Highlights: • The band gap of Lu₂WO₆ is calculated to be 3.13 eV using the CASTEP mode. • Valent state and occupation site of Eu are clarified by X-ray absorption fine structure (XAFS) spectra. • The thermal/concentration quenching mechanisms of Eu in Lu₂WO₆ have been investigated in detail. - Abstract: Density functional theory calculations on monoclinic Lu₂WO₆ is carried out using the Cambridge Sequential Total Energy Package code. The result indicates that Lu₂WO₆ is a broad band gap semiconductor with an indirect band gap of 3.13 eV. Eu ions are trivalency and the average coordination number is 7.6(5), indicating that the site of Lu is occupied by Eu. The activation energy ΔE is calculated as 0.314 eV. In addiation, the thermal quenching mechnism of Eu-activated Lu₂WO₆ and the different concentration quenching mechanisms for ⁵D₀ and ⁵D₁ emissions of Eu ions have been proposed