Ba 치환에 따른 (Ru,Cu)(Sr,Eu)2(Eu,Ce)2Cu2Oz 계의 초전도 특성

초록

We investigated the effects of Ba and Cu co-substitution on the structural and superconducting properties of (Ru1-yCuy)(Sr1.67-xBaxEu0.33)(Eu1.34Ce0.66)Cu2Oz samples. X-ray diffraction(XRD) reveals that single-phase samples can be obtained in the range from x = 0.1 to 0.2 for (Ru0.5Cu0.5)(Sr1.67-xBaxEu0.33)(Eu1.34Ce0.66)Cu2Oz and from y = 0.25 to 0.5 for (Ru1-yCuy)(Sr1.47Ba0.2Eu0.33)(Eu1.34Ce0.66)Cu2Oz, respectively. All samples with compositions of (Ru0.5Cu0.5)(Sr1.67-xBaxEu0.33)(Eu1.34Ce0.66)Cu2Oz (x = 0 - 0.33) show superconducting transition behavior and the onset transition temperature decreases slightly with increasing x in consistent with the change of hole concentration estimated from room temperature thermoelectric power measurements. The XRD and resistivity measurements for the (Ru1-yCuy)(Sr1.47Ba0.2Eu0.33)(Eu1.34Ce0.66)Cu2Oz system indicate that the partial substitution of Cu for Ru is necessary to form phase pure samples, but result in a small change in transition temperature in the single-phase region from x = 0.25 to 0.5.

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