Effects of Ru Addition on the Superconducting Properties of the Eu-123 System

Effects of the Ru addition on the structural and superconducting properties of the Eu-123 system were studied. Samples of the nominal composition $EuBa₂Cu_{3-x}Ru_{x}O_{7-δ}$ with x ranging from 0.0 to 0.7 were prepared by the solid state reaction technique from Eu₂O₃, BaCO₃, CuO and RuO₂ precursors at the temperature of 1050°C for 72 h in flowing oxygen and oxygen-annealed at 580°C for 24 h. X-ray diffraction data show the presence of another Ba-Eu-Ru-O phase, for x ≥ 0.03, in addition to the main superconducting phase. AC and DC magnetization characteristics were measured by the compensation method using the second-order SQUID gradiometer at ≈ 77 K and the QD SQUID magnetometer MPMS XL-7 at 20 K. The superconducting properties, $T_{c}$, $ΔT_{c}$, change only weakly up to x = 0.2, and magnetization M(H) deteriorates with an increasing Ru content.