LiFeAs Pnictide Superconductor—A Simple Electrochemical Method of Preparation

Unlike the known isoelectronic undoped intrinsic FeAs compounds, LiFeAs does not show any spin-density wave behavior but exhibits superconductivity at ambient pressures without chemical doping. It has a superconducting transition temperature, T_c, of 18 K with electron-like carriers and a very high 0 K upper critical magnetic field, B_c2(0), of greater than 80 T making the compound suitable for many high magnetic field applications at cryogenic temperatures. Oxypnictide materials are known for a complexity of their methods of preparation. The reported methods of LiFeAs preparation are based on the solid-state reaction at high temperatures (740 °-1050 °C) for long times (24-60 h). In the present work a simple electrochemical route is proposed for the preparation of a pnictide LiFeAs superconductor. During electrolysis, Li ions in the electrolyte become inserted into the FeAs lattice to form LiFeAs on the surface of the FeAs electrode. The proposed method differs from the existing electrochemical method and also from the traditional high temperature solid-state reaction methods. It is promising for the preparation of LiFeAs bulks and large scale LiFeAs films or tapes for various electric power or high magnetic field applications at cryogenic temperatures.