The ternary Zr–Pt–Sb system

The isothermal cross-section of the phase diagram of the ternary Zr–Pt–Sb system in the whole concentration range at 600 °C has been investigated by means of X-ray analysis. The samples were prepared by arc-melting of the pure elements under argon atmosphere with further annealing in evacuated silica tubes at 600 °C for 720 h followed by quenching in cold water. Five new compounds were discovered in this system: Zr6PtSb2 (Zr6CoAl2-type, P6¯2m, a = 7.797(2) Å, c = 3.716(2) Å), ZrPt2−xSb (MnCu2Al-type, Fm3¯m, a = 6.3205(7) Å), Zr9Pt9Sb2 (Zr9Pt11-type, I4/m, a = 10.4118(8) Å, c = 7.0250(8) Å), Zr5PtSb2 (tetragonal, a = 11.0721(8) Å, c = 5.5369(6) Å), and ∼Zr2Pt2Sb (unknown structure). The existence of two previously known compounds, Zr5PtSb3 (Hf5CuSn3-type, P63/mcm, a = 8.634(2) Å, c = 5.805(2) Å) and Zr3Pt3Sb4 (Y3Au3Sb4-type, I4¯3d, a = 9.4205(8) Å), was confirmed. The homogeneity ranges were determined to be x = 0.4–0.6 for ZrPt2−xSb and x = 0.57–1.0 for Zr5PtxSb3.