Synthesis and mid-infrared luminescence of “mixed” Er:(Lu,Y,La)2O3 transparent ceramic

We report on the synthesis and a detailed spectroscopic study of an Er³⁺ -doped “mixed” (Lu,Y,La)2O3 transparent sesquioxide ceramic. Nanopowders of the composition (Lu_0.63Y_0.25La_0.05Er_0.07)2O3 were obtained by a glycine-nitrate self-propagating high-temperature synthesis. The ceramics were obtained by vacuum sintering at 1750 °C for 3 hours. La₂O₃ acted as a sintering additive and increased the disorder of the sesquioxide lattice. The ceramic had a cubic (C-type) structure. At 1.05 μm, its transmission was 78.9%. The ceramic exhibited intense mid-infrared emission owing to the ⁴ I_11/2 → ⁴ I_13/2 Er ³⁺ transition. The corresponding peak stimulated-emission cross-section σSE is 1.12×10-20 cm² at 2717 nm. The luminescence spectrum exhibited a considerable inhomogeneous broadening as compared to the parent compounds, Er:Lu₂O₃ and Er:Y₂O₃. The luminescence lifetimes of the ⁴ I_11/2 and ⁴ I_13/2 manifolds were measured (1.99 ms and 3.35 ms, respectively), representing a favorable ratio for mid-IR laser operation. The crystal-field splitting of Er³⁺ multiplets in C₂ sites was determined at low temperature.