Synthesis and upconversion luminescence spectra of (Y1–x–yYbxEry)2O2S solid solutions

Abstract

Sequentially exposing coprecipitated yttrium, ytterbium, and erbium sulfates to flowing H₂ at 500–600°C for 6 h and then to flowing H₂S at 1000°C for ≤7 h, we obtained single-phase samples of the following solid solutions: (1) (Y_0.97Er_0.02Yb_0.01)₂O₂S (а = 3.779 Å, с = 6.579 Å), (2) (Y_0.94Er_0.05Yb_0.01)₂O₂S (а = 3.783 Å, с = 6.572 Å), (3) (Y_0.91Er_0.07Yb_0.02)₂O₂S (а = 3.775 Å, с = 6.568 Å), (4) (Y_0.87Er_0.10Yb_0.03)₂O₂S (а = 3.772 Å, с = 6.559 Å), (5) (Y_0.82Er_0.15Yb_0.03)₂O₂S (а = 3.770 Å, с = 6.545 Å), and (6) (Y_0.96Yb_0.03-Er_0.01)₂O₂S (a = 3.780 Å, c = 6.580 Å). The observed chemical transformations were accompanied by a transition from powder particles 2–25 μm in size to agglomerates 30–50 μm in size. The upconversion luminescence intensity in the samples was found to have a maximum: 400 (1), 3750 (2), 2100 (3), 1100 (4), and 150 arb. units (5). The presence of (Y_0.96Yb_0.03Er_0.01)₂O₃ and (Y_0.96Yb_0.03Er_0.01)₂S₃ as impurity phases in the samples was shown to considerably reduce the luminescence intensity.