Diversity of Microstructural Phenomena in Superconducting and Non-superconducting RbxFe2鈥?i>ySe2: A Transmission Electron Microscopy Study at the Atomic Sca

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• 作者：Maria V. Roslova ; Oleg I. Lebedev ; Igor V. Morozov ; Saicharan Aswartham ; Sabine Wurmehl ; Bernd B眉chner ; Andrei V. Shevelkov
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：December 16, 2013
• 年：2013
• 卷：52
• 期：24
• 页码：14419-14427
• 全文大小：476K
• 年卷期：v.52,no.24(December 16, 2013)
• ISSN：1520-510X

文摘

Superconducting (SC) and non-superconducting (non-SC) Rb_xFe_2鈥?i>ySe₂ crystals were grown using the 鈥渟elf-flux鈥?technique in order to assign the microstructural changes to the onset of superconductivity in complex iron selenides. The crystals were thoroughly characterized by magnetic susceptibility and transport measurements as well as powder X-ray diffraction. Special attention was paid to the comparison of the microstructure of the crystals with and without the superconducting transition by means of transmission electron microscopy (TEM). It is shown that the alternation of ordered and disordered regions on the sample surface and along the c-axis is characteristic for both SC and non-SC materials and therefore does not necessarily represent a trigger of superconductivity. Three types of electron diffraction patterns were found for the superconducting Rb_xFe_2鈥?i>ySe₂ sample, of which one is observed for the first time and originates from alkali metal ordering. Moreover, for the superconducting Rb_xFe_2鈥?i>ySe₂ material a monoclinic distortion with 尾 87掳 was observed, leading to the space group I2/m. This monoclinic distortion seems to be an attribute of the superconducting material only, whereas in the non-superconducting sample the orthogonality of the crystallographic axes is preserved.