Iron-Based Core-Shell Nanoparticles With Shell-Enhanced Coercivity
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Solution Overview
Problem
Current permanent magnets rely on rare earth elements, which are scarce, expensive, and environmentally harmful to mine, and are difficult to manufacture, particularly the Fe 16 N 2 phase with high magnetic anisotropy and saturation magnetization.
Innovation Solution
The development of core-shell nanoparticles with an iron-based core, such as Fe 16 N 2, and a non-magnetic, anti-ferromagnetic, or ferrimagnetic shell, which enhances coercivity through strain, exchange, magnetocrystalline, and shape anisotropies, and can be formed using techniques like immersion in a salt composition or milling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If rare earth elements (neodymium) are used in permanent magnets, then high energy product is achieved, but supply availability and cost increase
Solution Approach 1:
The patent changes the chemical composition parameters by replacing rare earth elements with iron-based compounds (Fe16N2, Fe8N phases) that have different magnetic properties. By adjusting nitrogen content and heat treatment parameters, the iron-based magnets achieve high energy product comparable to rare earth magnets while eliminating supply availability concerns
Solution Approach 2:
The patent substitutes expensive rare earth elements with inexpensive iron and nitrogen, which are abundant and widely available. The iron-based nanoparticles provide the necessary magnetic properties at lower cost without relying on scarce strategic materials
2Use of energy by moving object
If rare earth elements are used in permanent magnets, then high energy product is achieved, but manufacturing cost increases
Solution Approach 1:
The patent changes material composition from rare earth-based to iron-based (Fe16N2/Fe8N phases) and optimizes processing parameters including low-temperature heat treatment (below 500°C) and controlled nitrogen infiltration, resulting in reduced manufacturing cost while maintaining high energy product
Solution Approach 2:
The patent replaces expensive rare earth elements with cheap iron and nitrogen materials. The simplified composition eliminates the need for costly rare earth mining, processing, and handling operations, significantly reducing overall manufacturing cost
3Use of energy by moving object
If rare earth elements are used in permanent magnets, then high energy product is achieved, but environmental deterioration occurs
Solution Approach 1:
The patent changes the material system from rare earth-based to iron-based (Fe16N2/Fe8N phases), eliminating the need for environmentally harmful rare earth mining operations. The new material composition achieves comparable energy product without the associated environmental damage
Solution Approach 2:
The patent extracts and eliminates rare earth elements from the magnetic material composition, replacing them with iron-based compounds. This extraction removes the source of environmental deterioration associated with rare earth mining while preserving the essential magnetic functionality
4Use of energy by moving object
If Fe16N2 phase is manufactured using conventional methods, then high magnetic anisotropy and saturation magnetization are achieved, but manufacturing difficulty increases
Solution Approach 1:
The patent segments the Fe16N2 phase formation into controlled stages: first forming iron nanoparticles, then infiltrating with nitrogen source, and finally applying low-temperature heat treatment. This segmentation simplifies the manufacturing process compared to conventional high-temperature sintering methods
Solution Approach 2:
The patent changes the processing parameters by using low-temperature heat treatment (below 500°C) instead of conventional high-temperature sintering (>1000°C). This parameter change reduces manufacturing difficulty while achieving the desired Fe16N2 phase with high magnetic anisotropy and saturation magnetization
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
These core-shell nanoparticles achieve magnetic properties comparable to or exceeding those of rare-earth magnets, including high coercivity and energy product, without using rare earth elements, thus addressing supply and environmental concerns.
Implementation Method 1
enhances coercivity through strain, exchange, magnetocrystalline, and shape anisotropies
Implementation Method 2
enhances coercivity through strain, exchange, magnetocrystalline, and shape anisotropies
Implementation Method 3
enhances coercivity through strain, exchange, magnetocrystalline, and shape anisotropies
Implementation Method 4
enhances coercivity through strain, exchange, magnetocrystalline, and shape anisotropies
Implementation Method 5
annealing a material including iron and nitrogen in the presence of an applied magnetic field to form at least one Fe 16 N 2 phase domain
Implementation Method 6
annealing a material including iron and nitrogen in the presence of an applied magnetic field to form at least one Fe 16 N 2 phase domain
Data Source
Figure 1A~3
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Figure 5
AI summary
Example nanoparticles may include an iron-based core, and a shell. The shell may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example alloy compositions may include an iron-based grain, and a grain boundary. The grain boundary may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example techniques for forming iron-based core-shell nanoparticles may include depositing a shell on an iron-based core. The depositing may include immersing the iron-based core in a salt composition for a predetermined period of time. The depositing may include milling the iron-based core with a salt composition for a predetermined period of time. Example techniques for treating a composition comprising core-shell nanoparticles may include nitriding the composition.