Polycrystalline Fe-Based Superconducting Magnets for High Trapped Fields
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Solution Overview
Problem
Current superconducting materials, such as permanent magnets and polycrystalline bulks, are limited in generating magnetic fields above 1 Tesla, making them inadequate for high-field applications and costly when electromagnets are used, while existing iron-based superconductors face current blocking issues due to grain boundaries, restricting their size and effectiveness.
Innovation Solution
The development of doped superconducting (AE) Fe2As2 compounds in a polycrystalline form, where AE denotes alkaline earth metals like Ba, Sr, and Ca, which can be magnetized to produce bulk trapped magnetization scaling with size, achieving magnetic fields greater than 1 Tesla and potentially over 10 Tesla with geometric versatility and improved magnetic field trapping at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional permanent magnets are used, then they are simple and inexpensive, but they can only generate magnetic fields up to approximately 1 Tesla
Solution Approach 1:
The patent changes the fundamental parameter of magnetic field generation by transitioning from ferromagnetic permanent magnets to superconducting materials. The iron-based superconductor (AE)Fe2As2 exhibits superconductivity at temperatures above 20 K, enabling magnetic field generation through persistent currents rather than magnetic saturation, thereby achieving fields exceeding 1 Tesla while maintaining operational simplicity
Solution Approach 2:
The patent employs composite material strategy by combining alkaline earth metals (AE = Ba, Sr, Mg, Ca) with iron and arsenic to create doped iron-based superconducting compounds. This composite approach optimizes both the superconducting properties and mechanical characteristics, enabling the material to generate high magnetic fields while maintaining structural integrity and geometric versatility
2Force
If electromagnets are used to generate magnetic fields above 1 Tesla, then higher magnetic fields are achieved, but implementation cost greatly increases
Solution Approach 1:
The patent implements continuous useful action through persistent currents in the superconducting material. Once the iron-based superconductor is magnetized, the supercurrents flow without resistance indefinitely, maintaining the magnetic field without continuous energy input. This eliminates the need for continuous power supply required by electromagnets, dramatically reducing operational energy consumption while sustaining high magnetic fields above 1 Tesla
Solution Approach 2:
The patent exploits the phase transition to superconducting state at temperatures above 20 K to enable lossless current flow. By operating in the superconducting phase rather than the normal resistive phase, the material allows persistent currents that generate magnetic fields without continuous energy expenditure, contrasting with electromagnets that require continuous electrical power input
3Force
If iron-based superconductors are used, then high upper critical fields and critical current densities are achieved, but grain boundaries block current flow
Solution Approach 1:
The patent applies local quality principle by optimizing the microstructure at the grain boundary level. Through controlled doping with alkaline earth metals and precise heat treatment, the grain boundaries are engineered to have enhanced superconducting properties rather than being mere defects. This local optimization ensures continuous current flow across grain boundaries while maintaining the high upper critical fields and critical current densities inherent to iron-based superconductors
4Force
If mechanically reinforced superconducting REBCO materials are used, then record levels of trapped magnetic fields are produced, but they are limited in size because grain boundaries block current flow
Solution Approach 1:
The patent changes the fundamental parameter of grain boundary behavior through alkaline earth metal doping. Unlike REBCO where grain boundaries are detrimental, the iron-based superconductor (AE)Fe2As2 with AE = Ba, Sr, Mg, or Ca exhibits enhanced current flow across grain boundaries due to modified electronic structure and pinned flux density. This parameter change enables large-scale magnets while maintaining high trapped magnetic fields, achieving both record levels of trapped field and geometric versatility with no practical size limitation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The Fe-based polycrystalline superconducting permanent magnets demonstrate enhanced magnetic field trapping capabilities, overcoming size limitations and current blocking issues, with predicted high-field performance exceeding current technologies, and showcasing scalability and mechanical strength through specific manufacturing processes.
Implementation Method 1
The bulk materials of the present invention can be magnetized in their superconducting state by induced currents, resulting in bulk trapped magnetization that scales with the size of the bulk material
Implementation Method 2
The bulk materials of the present invention can be magnetized in their superconducting state by induced currents
Implementation Method 3
polycrystalline materials which are synthesized of doped superconducting (AE) Fe2As2 compounds... achieving magnetic fields greater than 1 Tesla and predicted to be over 10 Tesla with geometric versatility and improved magnetic field trapping at lower temperatures
Data Source
AI summary
The present invention provides for polycrystalline superconducting permanent magnets which are synthesized of doped superconducting (AE) Fe2As2 compounds, where AE denotes an alkaline earth metal, such as Ba, Sr, Mg or Ca. The superconducting permanent magnets of the present invention can be magnetized in their superconducting state by induced currents, resulting in trapped magnetization that scales with the size of the bulk material. The magnitude of the trapped field has been demonstrated to be over 1 T and is predicted to be over 10 T if the technology is scaled, which is much higher than the capabilities of permanent magnets and other superconducting polycrystalline bulks currently known in the art.