Among all the Iron based superconductors (IBS) families the iron chalcogenides FeSexTe1-x, also called 11 phases, are the simplest, and they are quite attractive because of their relatively ease of fabrication and the absence of toxic arsenic. 11 thin films have been successfully grown on single crystalline substrates and on technical metallic templates with a complex architecture which have been developed and are already commercially available for the deposition of YBa2Cu3O7-x. In IBS the exponential decay of Jc across misoriented grain boundaries seems to be less severe than for YBCO. Moreover, 11 thin films are deposited without the presence of oxygen in a temperature range between 230°C and 550°C. These features have a strong impact on the development of a suitable Coated Conductors (CC) technology relaxing significantly the film texture constraint and the role of the buffer layer architecture. Another important aspect, beside the fabrication of a suitable cost-effective conductor that needs to be considered in view of high-field applications, is the effect of irradiation which is necessary to test the suitability of a conductor for operation in a radiation environment, such as fusion or accelerator magnets. We found that the effect of irradiation on superconducting properties of 11 thin films is generally small as compared to the case of other iron-based superconductors and that possible modifications induced by irradiation in the substrate may affect the superconducting properties of the film via lattice strain. In this context the thesis is focused on the development of 11 CC with simpler and cost-effective templates and on the study of the effects of proton irradiation on the 11 thin films. The different CC architecture studied are presented and the properties of the 11 thin films deposited on these substrates will be shown. Moreover, the effects of proton irradiation on films deposited on single crystal substrates are shown, giving a complete overview for the possible applications of the 11 phase at high magnetic field.

Development of iron based superconducting wires and tapes for high field applications

SYLVA, GIULIA
2020-03-20

Abstract

Among all the Iron based superconductors (IBS) families the iron chalcogenides FeSexTe1-x, also called 11 phases, are the simplest, and they are quite attractive because of their relatively ease of fabrication and the absence of toxic arsenic. 11 thin films have been successfully grown on single crystalline substrates and on technical metallic templates with a complex architecture which have been developed and are already commercially available for the deposition of YBa2Cu3O7-x. In IBS the exponential decay of Jc across misoriented grain boundaries seems to be less severe than for YBCO. Moreover, 11 thin films are deposited without the presence of oxygen in a temperature range between 230°C and 550°C. These features have a strong impact on the development of a suitable Coated Conductors (CC) technology relaxing significantly the film texture constraint and the role of the buffer layer architecture. Another important aspect, beside the fabrication of a suitable cost-effective conductor that needs to be considered in view of high-field applications, is the effect of irradiation which is necessary to test the suitability of a conductor for operation in a radiation environment, such as fusion or accelerator magnets. We found that the effect of irradiation on superconducting properties of 11 thin films is generally small as compared to the case of other iron-based superconductors and that possible modifications induced by irradiation in the substrate may affect the superconducting properties of the film via lattice strain. In this context the thesis is focused on the development of 11 CC with simpler and cost-effective templates and on the study of the effects of proton irradiation on the 11 thin films. The different CC architecture studied are presented and the properties of the 11 thin films deposited on these substrates will be shown. Moreover, the effects of proton irradiation on films deposited on single crystal substrates are shown, giving a complete overview for the possible applications of the 11 phase at high magnetic field.
20-mar-2020
Superconductivity; Iron Based Superconductors; Coated Conductors; Proton Irradiation
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11567/1000769
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