Adjustable photoluminescence of Bi3+ and Eu3+ in solid solution constructed by isostructural end components through composition and excitation-driven strategy

Abstract

• From orange red to blue in one phosphor via excitation-driven strategy. • The luminescence color of Bi 3+ was fine-tuned by solid solution composition. • Bi 3+ ions are used as doping ions, which can be carried out in air. • Solid solution constructed by isostructural end components. Most lanthanide doped phosphors need to be prepared in a reducing atmosphere, such as phosphors doped by Eu 2+ and Ce 3+ ions with d-f transition. In contrast, the doping ion Bi 3+ selected in this paper has more advantages. Moreover, the 6S electrons of bare bismuth are very sensitive to the surrounding coordination field environment, which makes it highly tunable. A new type of solid solution Sr 3−x Gd x AlO 4+x F 1−x designed by the isostructural end components Sr 3 AlO 4 F and GdSr 2 AlO 5 well promotes the luminescence of Bi 3+ ion. By adjusting the concentration of Bi 3+ /Eu 3+ , the phosphor can be tuned from blue to red, which is due to the energy transfer caused by dipole–dipole interaction between Bi 3+ and Eu 3+ . Surprisingly, by means of excitation-driven, the emission peak position of Bi 3+ ions can also be moved from ~425 nm to ~437 nm, and red shift occurs, so as to realize the tuning of the fluorescence from orange red to blue. We speculate that this is induced by the presence of multiple emission centers of Bi 3+ , and different absorption strength of Bi 3+ and Eu 3+ . In addition, the thermal response of Bi 3+ and Eu 3+ ions to temperature is different. They are thermally quenched by energy level cross relaxation (ELCR) and multi-phonon deexcitation (MPD), respectively. The maximum relative sensitivity of optical thermometry based on fluorescence intensity ratio (FIR) is approximately 1.17 %K −1 at 323 K, which is higher than that of previously reported Bi 3+ and Eu 3+ co-doped phosphors. At 523 K, we also obtained a high absolute sensitivity of 0.0064 K −1 . Consequently, the solid solution phosphor prepared by us has a far-reaching application prospect in the field of temperature monitoring.