Dual-Mode Manipulating Multicenter Photoluminescence in a Single-Phased Ba9Lu2Si6O24:Bi3+ Eu3+ Phosphor to Realize White Light/Tunable Emissions

摘要

A Bi³⁺ and Eu³⁺ ion co-doped Ba9Lu2Si6O24 single-phased phosphor was synthesized successfully via a conventional high-temperature solid-state reaction. X-ray diffraction, crystal structure analysis, diffuse reflectance and luminescent spectra, quantum efficiency measurements, and thermal stability analysis were applied to investigate the phase, structure, luminescent and thermal stability properties. From the analyses of the crystal structure and luminescent spectra, we observed four discernible Bi³⁺ luminescent centers with peaks at ~363.3, ~403.1, ~437.7, and ~494.5 nm. Moreover, due to the complex energy transfer processes among these Bi³⁺ centers, their relative emission intensity tightly depended on the incident excitation wavelength. Interestingly, the as-prepared phosphor could generate warm white light/tunable emission by changing the concentration of Eu³⁺ ions or adjusting the excitation wavelength. The energy transfer mechanism from Bi³⁺ to Eu³⁺ was confirmed via an electric dipole-dipole interaction, the energy transfer efficiencies (ηT) from Bi³⁺ to Eu³⁺ were 50.84% and 40.17% monitoring at 410 and 485 nm, respectively. The internal quantum efficiency of the optimized Ba9Lu2Si6O24:Bi³⁺, Eu³⁺ phosphor was calculated to be 42.6%. In addition, the configurational coordinate model was carried out to explain the energy decrease of the phonon-electron coupling effect.