NSF Award
2413045
Non-technical summary: <br/>Since high-temperature superconductors (HTS) were discovered and awarded a Nobel prize, many prototypes of electronic and electric applications based on HTS materials have been demonstrated. A great impact on reducing energy loss and environment impact is anticipated from adopting superconducting devices and systems, including fusion systems for clean energy, electric propulsion for electric aircrafts, wind-powered generators, high efficiency electric power grid, superconductor magnets for high-energy physics and NMR/MRI in medicine, etc. Significant market penetration of HTS technologies, however, requires performance-cost balanced HTS materials and demands basic material research to resolve the critical issues relevant to applications in achieving high superconducting critical current density, Jc. Growth of nanoscale impurities (so-called artificial pinning centers or APCs) in HTS matrix provides a powerful approach to raise Jc in APC/HTS nanocomposites, and the method can be directly implemented to large-scale commercial HTS devices and systems. The objective of this project, supported by the Ceramics Program in the Division of Materials Research at NSF, is to investigate the growth mechanism of APC/HTS nanocomposite films in a novel multilayer approach developed by this team for strain-field guided Ca diffusion to, and cation replacement on the HTS crystal lattice, aiming to achieve a precise control over the microstructure of the APC/HTS nanocomposites for enhanced Jc at high applied magnetic fields (H). The goal is to achieve high, H-orientation independent Jc in APC/HTS nanocomposites demanded for a variety of commercial applications ranging from lightweight electric-propulsion aircraft, to high-efficiency power grid, to environmental-friendly fusion, etc. The project emphasizes forefront workforce training in science and engineering and the cutting-edge research capability that integrates nanoscale material design, fabrication, modeling and characterization will attract high-quality students, especially those from underrepresented groups, to pursue careers in science and technology. <br/><br/>Technical summary: <br/>A long-standing question in superconductors is whether the theoretical depairing limit of superconducting critical current density Jc (so-called Jd) can be reached in high-temperature superconductors (HTS) through low-cost, controllable, strain-mediated, self-assembly of nanoscale APCs to pin the magnetic vortices with optimal efficiency. Addressing the challenge in approaching the Jd in APC/HTS nanocomposites demands understanding and controlling the strain fields at atomic to macroscopic scales. Such control cannot be achieved using the traditional trial-and-error approach. The proposed integrated modeling-synthesis-characterization approach represents a leap forward from the traditionally empirical one via materials by design. The recent success of this team in the development of a novel multilayer approach for strain-field guided Ca diffusion to, and cation replacement on the HTS Y123 (i.e. YBa2Cu3O7) crystalline lattice is a demonstration of this approach. Two integrated research themes are proposed focusing on understanding and manipulating strain fields towards controllable growth of APC/RE123 nanocomposite films for optimal critical temperature Tc and Jc in a strong magnetic field (H) approaching the theoretical depairing limit. Theme 1 will focus on modeling and simulation of the effect of Ca diffusion and cation replacement on the strain field in BaZrO3 1D-APC/RE123 multilayer nanocomposites, which will guide the sample synthesis by varying the nanocomposite structure design and processing parameters. Theme 2 consists of a workflow of characterization of strain field (Ca distribution and cation replacement, lattice constant, etc.) using advanced high-resolution electron microscopy-based characterization with the modeling and synthesis in Theme 1 to develop a machine-learning approach towards materials-by-design in superconductor nanocomposites for high, H-orientation independent Jc using a microscopic control of the strain field effect in APC/RE123 nanocomposites. The goal is to achieve a thorough understanding of strain-field guided Ca diffusion and cation replacement in tunning the strain field on the APC/Y123 multilayer nanocomposites towards achieving the Jd and a new material-by-design approach for a spectrum of functional ceramic materials.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
