The role of ferromagnetic cobalt tetraoxide (Co3O4) nanoparticles’ addition in (Cu0.5Tl0.5) Ba2Ca2Cu3O10-δ (CuTl-1223) superconductor was investigated via infield transport properties measurements. The solgel method was used for synthesis of Co3O4 nanoparticles and CuTl-1223 superconducting phase was prepared by solid-state reaction method. These Co3O4 nanoparticles were added in appropriate ratio to the precursor of CuTl-1223 superconducting matrix during its synthesis to get (Co3O4)x/CuTl-1223; x = 0, 0.25, 0.50, 1.00 and 2.00 wt% nanoparticle–superconductor composites. The crystal structure of bulk CuTl-1223 superconducting phase was observed not to be changed with the inclusion of Co3O4 nanoparticles, which indicated the dispersion and settlement of these nanoparticles across the grain boundaries of the host CuTl-1223 superconducting matrix. The increase in superconducting transition width and the decrease in activation energy deduced from in field dc-resistivity measurements with the inclusion of Co3O4 nanoparticles were the prominent indicatives of enhancement in flux dynamics. Thus Co3O4 nanoparticles of ferromagnetic nature act as anti-flux pinning agent in the host CuTl-1223 superconducting matrix.

中文翻译：

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Co3O4 纳米颗粒添加对 CuTl-1223 相场内超导性能的作用

通过场内传输特性测量研究了铁磁四氧化钴 (Co3O4) 纳米粒子在 (Cu0.5Tl0.5) Ba2Ca2Cu3O10-δ (CuTl-1223) 超导体中的添加作用。采用溶胶凝胶法合成Co3O4纳米颗粒，采用固相反应法制备CuTl-1223超导相。这些Co3O4纳米颗粒在CuTl-1223超导基质的合成过程中以适当的比例加入到其前驱体中，得到(Co3O4)x/CuTl-1223；x = 0、0.25、0.50、1.00 和 2.00 wt% 的纳米颗粒-超导体复合材料。观察到大量 CuTl-1223 超导相的晶体结构没有随着 Co3O4 纳米颗粒的加入而改变，这表明这些纳米颗粒在主体 CuTl-1223 超导基质的晶界上分散和沉降。超导跃迁宽度的增加和活化能的降低是由包含 Co3O4 纳米颗粒的现场直流电阻率测量得出的，这是通量动力学增强的突出表现。因此，铁磁性质的 Co3O4 纳米粒子在宿主 CuTl-1223 超导基质中充当抗通量钉扎剂。