Enhanced luminescence of La2LiSbO6: Cr3+ by Bi3+ and Yb3+ doping

Cr 3+ /Bi 3+ co-doped and Cr 3+ /Yb 3+ co-doped La 2 LiSbO 6 phosphors have been synthesized via a high-temperature solid-state method, respectively. La 2 LiSbO 6 : Cr 3+ gives a broadband emission peaking at 855 nm under 671 nm excitation. Partial substitution of La 3 ⁺ ions by Bi 3+ ions induces lattice distortion in the La 2 LiSbO 6 host and weakens the crystal field strength of Cr 3+ , leading to the red shift of Cr 3+ emission. The Cr 3+ emission peak shifts from 855 to 900 nm with Bi 3+ concentration increasing from 0 to 0.07 mol %. The increased lattice distortion also improves the local environment of Cr 3+ , thereby resulting in a threefold increase in luminescence intensity and a 25.8% increase in quantum yield. When the Yb 3+ ions are introduced, the emission peak can be further tuned from 855 to 1000 nm directly, induced by energy transfer from Cr 3+ to Yb 3+ ions. It is proven that quadrupole–quadrupole interaction is responsible for the energy transfer from Cr 3+ to Yb 3+ in the La 2 LiSbO 6 host. Moreover, the introduced Yb 3+ also largely improves the thermal stability of the phosphor. The work might provide meaningful reference for the design and development of highly efficient Cr 3+ -doped luminescent materials.