The Ternary System Eu2O3–SrO–CuO: Compounds and Phase Relations

Abstract

The subsolidus phase relations of the Eu2O3–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 nine three-phase regions and four two-phase regions. In this system, there exist two solid solutions, Sr14–xEuxCu24Oy and Eu1+xSr2−xCu2Oy, and one ternary compound, Eu0.8Sr1.2CuO3.4. The solid solution Sr14–xEuxCu24Oy (0≤x≤6) crystallizes in an orthorhombic unit cell with space group Fmmm and lattice constants of a=3.950–3.981 Å, b=11.475–11.298 Å, and c=13.401–12.827 Å. The solid solution Eu1+xSr2−xCu2Oy (0≤x≤0.4) belongs to an orthorhombic system with space group Immm and cell parameters a=3.761–3.775 Å, b=11.385–11.252 Å, and c=20.019– 20.069 Å. The ternary compound Eu0.8Sr1.2CuO3.4 crystallizes in an orthorhombic unit cell with space group Immm and lattice constants of a=3.713 Å, b=3.787 Å, and c=12.636 Å. A comparison of the Eu system with reported systems of La, Nd, Ho, and Y indicate that the phase diagrams become complicated with an increase in the lanthanide ion size.