The ternary system Gd 2O 3–SrO–CuO: compounds and phase relations

Abstract

The subsolidus phase relations of the Gd 2O 3–SrO–CuO ternary system have been investigated by X-ray powder diffraction. All samples were synthesized in air at 950–1000°C. The system can be divided into ten three-phase regions and two solid solutions. In this system, there exist two solid solutions: Sr 14− x Gd x Cu 24O y and Gd 1+ x Sr 2− x Cu 2O y and one ternary compound: GdSr 3Cu 2O y . The solid solution Sr 14− x Gd x Cu 24O y (0⩽ x⩽6.5) crystallizes in an orthorhombic structure cell with space group Fmmm and lattice constants of a=3.918(1)–3.975(1) Å, b=11.466(3)–11.282(1) Å and c=13.389(4)–12.832(1) Å. The solid solution Gd 1+ x Sr 2− x Cu 2O y (0⩽ x⩽0.3) belongs to an orthorhombic system with space group Immm, lattice constants a=3.755(1)–3.763(1) Å, b=11.354(4)–11.257(4) Å and c=20.008(4)–20.049(5) Å. The ternary compound (Gd 0.25Sr 0.75) 2CuO 4− δ crystallizes in an orthorhombic structure with space group Immm and lattice constants of a=3.7084(3) Å, b=3.7841(4) Å and c=12.6129(9) Å.