Topological superconductivity is of great contemporary interest and has been proposed in doped Bi₂Se₃, in which electron-donating atoms such as Cu, Sr or Nb have been intercalated into the Bi₂Se₃ structure. For Nb_xBi₂Se₃, with T_c ~ 3 K, it is assumed in the literature that Nb is inserted in the van der Waals gap. However, in this work an alternative origin for the superconductivity in Nb-doped Bi₂Se₃ is established. In contrast to previous reports, it is deduced that Nb intercalation in Bi₂Se₃ does not take place. Instead, the superconducting behaviour in samples of nominal composition Nb_xBi₂Se₃ results from the (BiSe)_1.10NbSe₂ misfit phase that is present in the sample as an impurity phase for small x (0.01 ≤ x ≤ 0.10) and as a main phase for large x (x = 0.50). The structure of this misfit phase is studied in detail using a combination of X-ray diffraction and transmission electron microscopy techniques.

拓扑超导性具有极大的当代意义，并已在掺杂的Bi ₂ Se _3中提出，其中将供电子原子（例如Cu，Sr或Nb）插入Bi ₂ Se ₃结构中。对于Nb _x Bi ₂ Se ₃，T _c〜3  K，在文献中假设Nb插入范德华间隙中。然而，在这项工作中，为掺Nb的Bi ₂ Se _3中的超导性建立了另一种起源。与以前的报告相反，可以推断出Nb嵌入Bi ₂ Se _3中没有发生。取而代之的是，在标称组成铌样品的超导行为_X的Bi ₂硒_3个从（碧色）结果_1.10 NbSe ₂失配相，其存在于该样品作为用于小杂质相在X（0.01≤  X  ≤0.10）和作为x的主要相位（x  = 0.50）。使用X射线衍射和透射电子显微镜技术的结合，详细研究了该失配相的结构。