This study reports results for the morphology, crystal structure and critical parameters of Sm₂O₃-doped MgB₂ wires with low and high initial filling densities. The transmission electron microscope (TEM) images were done for the longitudinal section of MgB₂ wires. The results show that the Sm₂O₃ admixture significantly changes the morphology of the MgB₂ material, accelerates the formation of the MgB₂ phase, does not form rectangular MgB₂ crystallites, does not leave pure Mg, and forms Sm₂O₃ areas of 10 nm and 20 nm. The effects of Sm₂O₃ addition on MgB₂ formation in superconducting wires were revealed in detail in this study. Additionally, Sm₂O₃ causes the formation of point pinning regions that significantly increase the critical transport current density at the temperature range from 15 K to 30 K. The TEM images point out that rectangular MgB₂ crystallites are formed in undoped MgB₂ wires, which have not been previously reported. XRPD results showed that short-term heating allowed obtaining a larger amount of MgB₂ phase for the MgB₂ wire with high initial filling density. On the other hand, long heating time and high initial density slow down the creation of MgB₂ phase when the Mg is in the solid state.

中文翻译：

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透射电子显微镜研究了 Sm2O3 掺杂剂对 MgB2 线结构、形貌和输运临界电流密度的影响


本研究报告了具有低初始填充密度和高初始填充密度的 Sm ₂ O ₃ 掺杂 MgB ₂ 线的形态、晶体结构和关键参数的结果。透射电子显微镜 （TEM） 图像对 MgB ₂ 线的纵截面进行了处理。结果表明，Sm ₂ O ₃ 外加剂显著改变了 MgB ₂ 材料的形貌，加速了 MgB ₂ 相的形成，不形成矩形 MgB ₂ 微晶，不留下纯 Mg，并形成 10 nm 和 20 nm 的 Sm ₂ O ₃ 区域。本研究详细揭示了 Sm ₂ O ₃ 添加对超导线中 MgB ₂ 形成的影响。此外，Sm ₂ O ₃ 会导致点固定区域的形成，从而在 15 K 至 30 K 的温度范围内显着增加临界传输电流密度。TEM 图像指出，矩形 MgB ₂ 微晶是在未掺杂的 MgB ₂ 线中形成的，这在以前没有报道过。XRPD 结果表明，短期加热允许为具有高初始填充密度的 MgB ₂ 线获得更大量的 MgB ₂ 相。另一方面，当 Mg 处于固态时，较长的加热时间和较高的初始密度会减慢 MgB ₂ 相的产生。