Synthesis, up-conversion luminescence and thermometry of Yb3+/Er3+ co-doped La2.4Mo1.6O8 phosphors

Abstract

Yb³⁺/Er³⁺ co-doped La_2.4Mo_1.6O₈ up-conversion phosphors with thermometric properties were synthesized by a conventional solid-state reaction. The optimal synthesis conditions for the pure phase have been determined by varying the types and contents of fluxes. Structural studies verify that all samples retain the same face-centered cubic structure, and the morphology via SEM observation also verified the cubic-like crystal growth behaviour. Yb³⁺/Er³⁺ co-doped La_2.4Mo_1.6O₈ phosphors mainly emit green emission peaks, ascribed to the emission from the excited states ²H_11/2 and ⁴S_3/2 to the ground state ⁴I_15/2 of Er³⁺ ion, and the weak red emission from the excited state ⁴F_9/2 to the ground state ⁴I_15/2 of Er³⁺ ion when they are excited by 980 nm laser diodes. The up-conversion process has been discussed in detail by pump-power dependence of luminescence intensities and further explained via the energy level diagram. The temperature-dependence properties of La_2.4Mo_1.6O₈ phosphors were investigated in detail, which show their potential prospect in temperature-sensing applications.