The effects of adding low-melting point metals (Pb, Sn, In and Ge) to polycrystalline CaKFe 4 As 4 (CaK1144) superconductors were investigated. We found that Sn is the most stable with CaK1144 among these low-melting point metals. Synthesis conditions as well as the doping quantity of Sn were optimized, and phase stability, microstructures and superconducting properties were investigated. At the optimized sintering temperature of 700 °C, Sn was effectively solidified in grain boundaries (GBs) of the CaK1144 bulk samples and secondary phase formations were not serious in optimized samples. As the Sn amount increased, filling of Sn in the GBs increased up to 30 wt% with homogeneous dispersion. The magnetic field dependence of critical-current density ( J c ) was significantly enhanced by 30 wt% Sn addition and decreased with further increase of Sn addition. The filling up of 1144 grain boundaries by the optimal amount of Sn enhanced the J ...

中文翻译：

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锡添加对CaKFe 4 As 4超导体的影响

研究了向多晶CaKFe 4 As 4（CaK1144）超导体中添加低熔点金属（Pb，Sn，In和Ge）的效果。我们发现在这些低熔点金属中，Sn对CaK1144最稳定。优化了合成条件和Sn的掺杂量，研究了相稳定性，微观结构和超导性能。在700℃的最佳烧结温度下，Sn在CaK1144块状样品的晶界（GBs）中有效固化，并且在优化样品中次生相的形成并不严重。随着Sn量的增加，GB中Sn的填充量增加至30 wt％，且分散均匀。临界电流密度（J c）的磁场依赖性通过添加30 wt％的Sn显着增强，并随着Sn添加的进一步增加而降低。通过最佳量的Sn填充1144晶界增强了J ...