Rasche Bertold, Yang Minjun, Nikonow Lothar, Cooper Joshaniel F K, Murray Claire A, Day Sarah J, Kleiner Karin, Clarke Simon J, Compton Richard G
Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, UK.
ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX, UK.
Angew Chem Int Ed Engl. 2019 Oct 21;58(43):15401-15406. doi: 10.1002/anie.201907426. Epub 2019 Sep 4.
We report the precise postsynthetic control of the composition of β-Fe Se by electrochemistry with simultaneous tracking of the associated structural changes via in situ synchrotron X-ray diffraction. We access the full phase width of 0.01<x<0.04 and identify the superconducting state below 8 K, which in contrast to earlier reports is independent of the composition. However, in a second set of in situ X-ray diffraction experiments, we demonstrate that β-Fe Se forms a new phase in the presence of oxygen above a 100 °C which has the same anti-PbO type structure but is not superconducting down to 1.8 K. The latter process can be reversed electrochemically to reinstate the superconducting state. These observations exploit the exquisite control afforded by electrochemistry in contrast with classical approaches of chemical synthesis.
我们报告了通过电化学对β-FeSe的成分进行精确的合成后控制，并通过原位同步加速器X射线衍射同时跟踪相关的结构变化。我们获得了0.01<x<0.04的全相宽度，并确定了低于8 K的超导状态，与早期报告不同的是，该超导状态与成分无关。然而，在第二组原位X射线衍射实验中，我们证明β-FeSe在高于100 °C的氧气存在下形成了一种新相，其具有相同的反PbO型结构，但在低至1.8 K时不超导。后一过程可以通过电化学逆转以恢复超导状态。与传统化学合成方法相比，这些观察结果利用了电化学提供的精确控制。
