Thesis proposals Fe based superconductors Syntesis of (Ba,K)Fe2As2 superconducting phase for applicationsThe discovery of superconductivity in Fe-based superconductors has generated enormous excitement in the field of superconductor applications. Many families of Fe-based materials that exhibit high-temperature superconductivity on appropriate doping have been discovered so far including REOFeAs(1111) (RE=rare earth element), FeSe (11) and BaFe2As2 (122). In addition to having high transition temperature, these compounds have very high upper critical fields, Hc2, making them promising for high filed applications. Among them the 122 family exhibits smaller anisotropy than the cuprate superconductors, making them attractive for magnet applications, because they are expected to have high irreversibility field, Hirr.. Furthermore this compound, in form of wire and bulk, has already shown the best performance in terms of Critical Current Density, JC, in applied magnetic field, maintaining values as high as 104 A/cm2 at field up to 15 T. To evaluate their real potential for practical applications, it is essential to develop a viable wire processing technique. Several groups from China and Japan are fabricating wires adapting the so called Powder-In-Tube (PIT) technique, already developed for the cuprates. However, large work is still needed to understand and solve several issues, both scientific and technological, such as grain connectivity, in order to realize wires with higher performances through an industrial appealing process. Our is the first European research group which is carrying on an activity on Fe-based superconducting wires and we propose a thesis whose aim is the realization of superconducting powders of the 122 family which can be used in the PIT technique for the fabrication of superconducting wires. The candidate will work on the synthesis and analysis of the powders, gaining familiarity with the use of glove-box and furnaces at high temperature in controlled atmosphere. Moreover, he will be involved on their characterization through several techniques: magnetic measurements by means of a Superconducting Quantum Interference Device (SQUID), structural analysis through X-Ray diffraction, chemical analysis through Scanning Electron Microscopy and Energy Dispersive X-Ray spectroscopy. Eventually, the candidate will be involved in the preparation and characterization of the first superconducting wire based on the best performing powders. The activities will take place at the CNR-SPIN laboratory and Physics Department.Referring: Dr. Malagoli, Prof. PuttiResearch group:Applied superconductivity' appliedLocation: CNR Spin, DIFIIdentification Code: 3Presented on 19/04/2021Available from 01/05/2021 Superconducting thin films Oriented metallic substrates for Fe-based superconductorsThe high field magnets are devices that "cannot do without" superconducting materials. They are used in many fields, from healthcare, in the nuclear magnetic resonance systems, to the plasma magnetic confinement, which is the basic concept of Fusion Power Reactors for energy generation, to energy storage systems. Moreover, accelerators for high energy physics push the development of magnets with increasing power. The challenge launched by CERN and China to build, by 2050, innovative accelerators more than ten times powerful with respect to LHC is currently driving the development of superconducting materials with increased performances. High-field magnets are still based on low temperature superconductors (LTS) and nowadays the main focus is on Nb3Sn, with maximum operating field of 20 T at 4.2 K. This value matches the current requests but sets a limit on further improvements. High temperature superconductors (HTS) present exceptional superconducting properties, which largely overcome these limits, but their performances decline fast with the structural disorder and they exhibit large anisotropy in their superconducting properties. Thus, fabrication of superconducting HTS wires/tapes is complicated and requires high cost.Iron-based superconductors (IBS)have characteristics in between LTS and HTS: relatively high critical temperatures Tc, up to 58 K, and huge upper critical fields Bc2 > 100 T. Moreover, they possess small anisotropy, superior inter-grain connectivity, tolerance to disorder and simplicity in the sample synthesis. These encouraging properties have pushed the research to explore the feasibility of IBS in practical conductors either wrapped inside a metal sheath through the powders in tube method (PIT) or deposited with textured microstructure on technical metallic substrates, the so-called coated conductors (CC). It has been shown that critical current density (Jc) values of 105 A/cm2 at 4.2K and 10 T, which is considered the target for industrial applications, can be achieved and surpassed.UniGe and CNR-SPIN institute are partners in a national PRIN (Projects of Significant National Interest) project named HiBiSCUS whose final aim is the realization of IBS-conductor prototypes that meet, in a reproducible way, the Jc requirements for industrial applications through reliable, simple and cheap techniques, as compared to the state-of-the-art technology. This project plans to implement the CC technology in order to overcome the current state-of-the-art. In such a context, we propose a thesis whose main aim is, through an innovative approach, the realization of a technical metallic substrates useful for the fabrication of cheaper, optimized and production-time-saving flexible IBS-CCs. More in detail, the candidate will work on the development of biaxially textured metallic substrates such as FeNi (INVAR) or Cu alloys. These templates, although much simpler to prepare than the complex heterostructures developed for YBCO-CC, will allow textured growth of IBSs, thus providing CCs free of grain boundaries acting as weak links to supercurrents. He will gain familiarity with the use of the machines for cold deformation as well as furnaces at high temperature in controlled atmosphere. Moreover, he will be involved on the substrate characterization through several techniques, such as structural analysis through X-Ray diffraction, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy. Eventually, the candidate will be involved in the preparation and characterization of the superconducting IBS-CCs grown on the best prepared metallic substrate. A close collaboration with other institutes such as ENEA, Politecnico di Torino and Università degli Studi ROMA 3 is planned as well. The activities will take place at the CNR-SPIN laboratory and Physics Department. Referents: Dr. Malagoli, Prof. PuttiResearch group:Applied superconductivity' appliedLocation: CNR Spin, DIFIIdentification code: 2Presented on 19/04/2021Available from 01/05/2021. Superconducting wires and tapes Syntesis of (Ba,K)Fe2As2 superconducting phase for applicationsThe discovery of superconductivity in Fe-based superconductors has generated enormous excitement in the field of superconductor applications. Many families of Fe-based materials that exhibit high-temperature superconductivity on appropriate doping have been discovered so far including REOFeAs(1111) (RE=rare earth element), FeSe (11) and BaFe2As2 (122). In addition to having high transition temperature, these compounds have very high upper critical fields, Hc2, making them promising for high filed applications. Among them the 122 family exhibits smaller anisotropy than the cuprate superconductors, making them attractive for magnet applications, because they are expected to have high irreversibility field, Hirr.. Furthermore this compound, in form of wire and bulk, has already shown the best performance in terms of Critical Current Density, JC, in applied magnetic field, maintaining values as high as 104 A/cm2 at field up to 15 T. To evaluate their real potential for practical applications, it is essential to develop a viable wire processing technique. Several groups from China and Japan are fabricating wires adapting the so called Powder-In-Tube (PIT) technique, already developed for the cuprates. However, large work is still needed to understand and solve several issues, both scientific and technological, such as grain connectivity, in order to realize wires with higher performances through an industrial appealing process. Our is the first European research group which is carrying on an activity on Fe-based superconducting wires and we propose a thesis whose aim is the realization of superconducting powders of the 122 family which can be used in the PIT technique for the fabrication of superconducting wires. The candidate will work on the synthesis and analysis of the powders, gaining familiarity with the use of glove-box and furnaces at high temperature in controlled atmosphere. Moreover, he will be involved on their characterization through several techniques: magnetic measurements by means of a Superconducting Quantum Interference Device (SQUID), structural analysis through X-Ray diffraction, chemical analysis through Scanning Electron Microscopy and Energy Dispersive X-Ray spectroscopy. Eventually, the candidate will be involved in the preparation and characterization of the first superconducting wire based on the best performing powders. The activities will take place at the CNR-SPIN laboratory and Physics Department.Referents: Dr. Malagoli, Prof. PuttiResearch group:Applied superconductivity' appliedLocation: CNR Spin, DIFIIdentification Code: 3Presented on 19/04/2021Available from 01/05/2021 metallic oriented templates Oriented metallic substrates for Fe-based superconductorsThe high field magnets are devices that "cannot do without" superconducting materials. They are used in many fields, from healthcare, in the nuclear magnetic resonance systems, to the plasma magnetic confinement, which is the basic concept of Fusion Power Reactors for energy generation, to energy storage systems. Moreover, accelerators for high energy physics push the development of magnets with increasing power. The challenge launched by CERN and China to build, by 2050, innovative accelerators more than ten times powerful with respect to LHC is currently driving the development of superconducting materials with increased performances. High-field magnets are still based on low temperature superconductors (LTS) and nowadays the main focus is on Nb3Sn, with maximum operating field of 20 T at 4.2 K. This value matches the current requests but sets a limit on further improvements. High temperature superconductors (HTS) present exceptional superconducting properties, which largely overcome these limits, but their performances decline fast with the structural disorder and they exhibit large anisotropy in their superconducting properties. Thus, fabrication of superconducting HTS wires/tapes is complicated and requires high cost.Iron-based superconductors (IBS)have characteristics in between LTS and HTS: relatively high critical temperatures Tc, up to 58 K, and huge upper critical fields Bc2 > 100 T. Moreover, they possess small anisotropy, superior inter-grain connectivity, tolerance to disorder and simplicity in the sample synthesis. These encouraging properties have pushed the research to explore the feasibility of IBS in practical conductors either wrapped inside a metal sheath through the powders in tube method (PIT) or deposited with textured microstructure on technical metallic substrates, the so-called coated conductors (CC). It has been shown that critical current density (Jc) values of 105 A/cm2 at 4.2K and 10 T, which is considered the target for industrial applications, can be achieved and surpassed.UniGe and CNR-SPIN institute are partners in a national PRIN (Projects of Significant National Interest) project named HiBiSCUS whose final aim is the realization of IBS-conductor prototypes that meet, in a reproducible way, the Jc requirements for industrial applications through reliable, simple and cheap techniques, as compared to the state-of-the-art technology. This project plans to implement the CC technology in order to overcome the current state-of-the-art. In such a context, we propose a thesis whose main aim is, through an innovative approach, the realization of a technical metallic substrates useful for the fabrication of cheaper, optimized and production-time-saving flexible IBS-CCs. More in detail, the candidate will work on the development of biaxially textured metallic substrates such as FeNi (INVAR) or Cu alloys. These templates, although much simpler to prepare than the complex heterostructures developed for YBCO-CC, will allow textured growth of IBSs, thus providing CCs free of grain boundaries acting as weak links to supercurrents. He will gain familiarity with the use of the machines for cold deformation as well as furnaces at high temperature in controlled atmosphere. Moreover, he will be involved on the substrate characterization through several techniques, such as structural analysis through X-Ray diffraction, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy. Eventually, the candidate will be involved in the preparation and characterization of the superconducting IBS-CCs grown on the best prepared metallic substrate. A close collaboration with other institutes such as ENEA, Politecnico di Torino and Università degli Studi ROMA 3 is planned as well. The activities will take place at the CNR-SPIN laboratory and Physics Department. Referents: Dr. Malagoli, Prof. PuttiResearch group:Applied superconductivity' appliedLocation: CNR Spin, DIFIIdentification code: 2Presented on 19/04/2021Available from 01/05/2021.
