Abstract Fe x Se superconducting bulks with different norminal Fe content from x = 1.00 to 1.20 have been fabricated with high-energy ball milling (HEBM) aided sintering process. The influences of original Fe contents on the phase composition, microstructures and superconducting properties were systematically investigated. It was noticed that with the increase of original Fe content, the nonsuperconducting δ-FeSe phase content decreased, while the content of residual Fe increased correspondingly. Meanwhile, the increasing original Fe content could also cause the increase of FeSe crystal size, therefore, the (00 l ) texture of FeSe bulks was enhanced, which would be beneficial to the intergrain connections. Mossbauer spectra have been performed to study the magnetic orders in obtained FeSe bulks. A clear hyperfine magnetic sextet corresponding to the magnetic ordering with H f of 333.0 kOe can be related to residual Fe in the bulks with Fe content higher than 1.10. The magnetic and superconducting properties of obtained bulks underwent a systematical change with original Fe content. The increasing Fe content can obviously enhance the superconducting performance of FeSe bulks and the optimal critical temperature, T c of 9.0 K was obtained with original Fe content of 1.20.

中文翻译：

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Fe含量对高能球磨辅助烧结工艺制备FeSe超导体的影响

摘要 通过高能球磨 (HEBM) 辅助烧结工艺制备了具有不同标准 Fe 含量从 x = 1.00 到 1.20 的 Fe x Se 超导块体。系统地研究了原始Fe含量对相组成、显微组织和超导性能的影响。注意到随着原始Fe含量的增加，非超导δ-FeSe相含量减少，而残余Fe含量相应增加。同时，原始Fe含量的增加也会导致FeSe晶体尺寸的增加，因此，FeSe块体的（00 l ）织构增强，有利于晶间连接。已进行穆斯堡尔谱以研究获得的 FeSe 块体中的磁序。与 H f 为 333.0 kOe 的磁序相对应的清晰超精细磁性六重奏可能与 Fe 含量高于 1.10 的块体中的残留 Fe 有关。获得的块体的磁性和超导性质随着原始 Fe 含量发生了系统性变化。增加Fe含量可以明显提高FeSe块体的超导性能，最佳临界温度T c 为9.0 K，原始Fe含量为1.20。