The evolution and role of Na₂CO₃ flux used to synthesize Er₂O₂S laser absorbent

A novel 1.54 μm laser absorbent of Er₂O₂S was prepared by solid state flux method. The effects of different calcining temperatures and preservation time on the synthesis and reflecting property of Er₂O₂S were investigated. The mechanism of fluxing agent was assumed and proved. The phase composition, morphology, and reflectivity of the powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet visible spectrophotometer (UV-3600PC). The results showed that pure phase of Er₂O₂S could be obtained with Na₂CO₃ as fluxing agent at 800–1200 °C, too high temperature and too long preservation time were bad for synthesizing Er₂O₂S. Na₂CO₃ played an important role during the reaction, the elemental sulfur in Er₂O₂S came from Na₂S₂O₃ indeed. Different calcination conditions had a great impact on particle morphology, which had influence on the reflectivity of the products. The reflectivity was the lowest (0.39 %) when the calcining temperature was 1200 °C.