Thermal behaviour and microstructural characterization of lanthanide sulphides

Thermal decomposition processes of rare earth sesquisulfides Ln₂S₃ (Ln= Lu, Y and Er) in O₂ flow up to 1590 K, have been studied. Decomposition takes place through incomplete oxidations and overlapping decomposition reactions. Two intermediate phases such as Ln₂O₂S and Ln₂O₂SO₄ are formed before the final more stable phase Ln₂O₃ (C-type) is obtained. Microstructural studies show the poor crystallinity of the intermediate products.We wish to thank the Centro de Microscopia Electrónica, U.C.M.) for facilities. This research was supported by the CYCIT project MAT 89-0768.