The role of Yb3+ concentrations on Er3+ doped SrLaMgTaO6 double perovskite phosphors

Abstract

Er³⁺, Yb³⁺ co-doped SrLaMgTaO₆ phosphors have been synthesized by a solid state reaction method. Under a 975 nm excitation, the SrLaMgTaO₆:Er³⁺/Yb³⁺ phosphors exhibited strong green luminescence centered at 525 nm and 545 nm and relatively weak red anti-stokes luminescence centered at 660 nm. Herein, we have established the upconversion mechanism based on the down conversion and upconversion photoluminescence (UCPL) properties. The sensitized energy upconversion [s-ETU2: Yb³⁺ (²F_5/2) + Er³⁺ (⁴I_11/2) → Yb³⁺ (²F_7/2) + Er³⁺ (⁴F_7/2)] is a main route of green UCPL, and the energy back transfer [EBT: Er³⁺ (⁴S_3/2) + Yb³⁺ (²F_7/2) → Er³⁺ (⁴I_13/2) + Yb³⁺ (²F_5/2)] is a main route of red UCPL, which reduces the green UCPL to a certain degree. The reduced green and red UCPL of the sample with a high concentration of Yb³⁺ is mainly attributed to the concentration quenching of the Yb³⁺ ion.