Synthesis of superconducting phase in FeSe by Spark Plasma Sintering for trapped field applications
Résumé
The development of the sintering process for the synthetization of superconducting Iron-selenide (FeSe) polycrystal enables a quick and cheap fabrication of superconducting bulks for trapped field applications without the use of Rare Earths or toxic elements. A relevant number of papers were published in the literature in order to determine the best way to produce a pure β-phase, responsible of the superconductivity without any other non-desirable phases (α-FeSe, unreacted Fe, FeSe – also called δ-FeSe). Using the collected information, we produced a pure β-phase by classic sintering process at temperatures above 685°Cfollowed by annealing below 450°C for optimizing the sample and improvement of the critical currents. Using the Spark Plasma Sintering method enables an improved homogeneity and a better grain coupling, which leads to a higher quality for FeSe superconducting bulks and an increased sample density. The consequence is another increase of the critical currents which makes the samples competitive for trapped bulks applications.