Phase diagrams of the Ln2S3-EuS (Ln = La-Gd) systems

The phase diagrams of the Ln2S3-EuS (Ln = La-Gd) systems were studied. In these systems, continuous series of solid solutions form between γ-Ln2S3 and EuLn2S4 (Th3P4 structural type), and also eutectics between EuLa2S4 and a solid solution based on EuS form at the following coordinates: 71.5 mol % EuS, 2280 K; 66.5 mol % EuS, 2240 K; and 63.5 mol % EuS, 2100 K. The characteristics of the forming compounds are the following: EuLa2S4: a = 0.8759 nm, Tmelt = 2420 K, and H = 2380 MPa; EuNd2S4: a = 0.8615 nm, Tmelt = 2380 K, and H = 2530 MPa; and EuGd2S4: a = 0.8507 nm, Tmelt = 2300 K, and H = 2670 MPa.