ABSTRACT

(BaSnO₃)_x/Cu_0.5Tl_0.5Ba₂Ca₂Cu₃O_10-δ superconducting composites (0.00 ≤ x ≤ 1.50 wt.%) were prepared by the solid-state reaction technique. The crystalline structure and superconducting transition temperature were investigated by X-ray powder diffraction (XRD) and dc-electrical resistivity measurements, respectively. X-Band electron spin resonance (ESR) measurements were carried out at different temperatures 103 ≤ T ≤ 298 K. ESR spectra are dominated by a single asymmetric line corresponding to Cu²⁺ ions at the rhombic site. The temperature dependence of the g factors allowed the determination of the pseudo-gap onset temperature T*. The results of T* are compatible with those obtained from resistivity and thermoelectric power measurements. The contribution of delocalized electrons from Cu²⁺ ions in the disordered part of the impurity phases BaCuO₂ and Ba₂CuO₃ is significant for the high addition of nanoparticles. Moreover, the number of spins N participating in ESR and the activation energy E_a were enhanced with the addition of BaSnO₃.

摘要

(BaSnO ₃ ) _x /Cu _0.5 Tl _0.5 Ba ₂ Ca ₂ Cu ₃ O _10-δ超导复合材料（0.00 ≤ x ≤ 1.50 wt.%）是通过固相反应技术制备的。分别通过 X 射线粉末衍射 (XRD) 和直流电阻率测量来研究晶体结构和超导转变温度。X 波段电子自旋共振 (ESR) 测量在 103 ≤ T ≤ 298 K 的不同温度下进行。 ESR 光谱由对应于 Cu ²⁺的单条不对称谱线支配菱形位点的离子。g 因子的温度依赖性允许确定伪间隙起始温度 T*。T* 的结果与从电阻率和热电功率测量中获得的结果一致。杂质相BaCuO ₂和Ba ₂ CuO ₃的无序部分中来自Cu ²⁺离子的离域电子的贡献对于纳米颗粒的高添加是显着的。此外，随着BaSnO ₃的加入，参与ESR的自旋数N和活化能E _a增加。