A high density CaKFe 4 As 4 bulk sample was successfully synthesized using a spark plasma sintering (SPS) technique. The density of the synthesized sample was 5.02 g cm −3 , corresponding to 96.2% of the theoretical density of CaKFe 4 As 4 . Moreover, a reasonably high Vickers hardness of 1 GPa was measured. The electrical resistivity of the SPS bulk sample was as low as approximately 600 μ Ω cm at 300 K, which is smaller than that of the ordinary sintered polycrystalline sample by nearly one order of magnitude, and exhibited a sharp superconducting transition with the transition width (Δ T c ) less than 2 K, indicating an improved grain connectivity. The critical current density of the SPS bulk sample calculated from the magnetization hysteresis loops (magnetic J c ) reached 18 kA cm −2 at 4.2 K under 5 T, which is the highest among the iron-based superconductor polycrystalline sample...

中文翻译：

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火花等离子体烧结技术合成高临界电流密度的CaKFe 4 As 4块状样品

使用火花等离子体烧结（SPS）技术成功合成了高密度CaKFe 4 As 4块状样品。合成样品的密度为5.02g cm -3，相当于CaKFe 4 As 4的理论密度的96.2％。此外，测得的维氏硬度相当高，为1 GPa。SPS块状样品在300 K时的电阻率低至约600μΩcm，比普通的烧结多晶样品的电阻率小近一个数量级，并且在跃迁宽度处表现出尖锐的超导跃迁（ ΔT c）小于2 K，表明改善了晶粒连通性。由磁化磁滞回线（磁性J c）计算出的SPS块状样品的临界电流密度在5 T下在4.2 K时达到18 kA cm -2，