Superconductivity at 40 K in Lithiation-Processed [(Fe,Al)(OH)₂][FeSe]_1.2 with a Layered Structure

Exploration of new superconductors has always been one the research directions in condensed matter physics. We report here a layered heterostructure [(Fe,Al)(OH)2][FeSe]1.2, which is synthesized by hydrothermal ion-exchange technique. The structure suggested combination X-ray powder diffraction and electron (ED). [(Fe,Al)(OH)2][FeSe]1.2 composed alternating stacking tetragonal FeSe layer hexagonal (Fe,Al)(OH)2 layer. In there exists mismatch between sublayer sublayer, lattice quasi-commensurate. as-synthesized nonsuperconducting due to Fe vacancies superconductivity with Tc 40 K can be achieved after lithiation process, elimination nearly same as that (Li,Fe)OHFeSe although quite different from (Li,Fe)OHFeSe. contains an iron selenium interleaved metal hydroxide lattice. These results indicate very robust for FeSe-based superconductors. It opens path exploring iron-base