Production and characterization of new generation fe-based superconducting alloys with single crystalline form and engineering application

Studies carried out within the scope of this thesis include two stages. In the first step, the 11- and 122-phases of Fe-based superconductors were produced in a "single crystal" form using the production method appropriate to the thermodynamic and phase transformation properties. In this context, firstly 11-phase of FeSe system was produced by "Chemical Vapor Transport (CVT)" method and the effects of different crystallization processes on single crystal quality and superconductivity properties were investigated.FeTe1-xSex (x = 0.1-0.4) materials obtained by partial substitution of Te element with Se in FeSe system and produced in single crystal form by "Self-Flux" method.Firstly, the effect of the change in the Te and Se sitochiometry on the superconducting parameters was investigated.Then, the effect of superconducting parameters on the produced single crystals was investigated by applying "O2-annealing" process.Finally, K0.8Fe2Se2, a 122-phase material, was produced in single crystal form by the addition of K+ alkali metal to the FeSe system and "One-Step" synthesis method.The K0.8Fe2Se2 system has been investigated for its crystallographic, electrical and magnetic properties.In the second stage of the thesis; Superconducting prototype coils (current coils), which are important applications in today's superconductor technology, have been produced and tested and at the end suitability of the coils produced in the engineering applications were discussed.