부산대학교 도서관

The possible difference in the properties upon doping the Sr2CaCu2O6 superconducting or blocking layers with Fe and Eu respectively was investigated in this work. The homogeneous Sr2−yEuyCaCu2O6+δ and Sr2CaCu2−xFexO6+δ (y = 0, 0.1, 0.5, x = 0, 0.05) compounds were produced by a high-pressure synthesis route. Judging by the magnetic susceptibility measurements, all samples exhibit a superconductivity transition and the Eu/Fe concentration dependencies on the diamagnetic moment and average Tc have been constructed using the experimental data. As a result, an unusual behavior of the Tc value was observed for the samples with doped Eu: a fivefold reduction in the europium concentration in the sample does not give a noticeable effect on the transition temperature value while the diamagnetic signal becomes more stronger. Complex superconducting dome was found for Eu-doped material: 0.1 ≤ y ≤ 0.5 region Tc vs. concentration data were approximated by inverted parabola-like curve with a maximum at y = 0.3. Difference in properties of the Eu and Fe-doped samples was also found in the behavior of the hysteresis loops showed the opposite orientations. [ABSTRACT FROM AUTHOR]