Magnetic Refrigeration Material With Wide Temperature Range
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Solution Overview
Problem
Current magnetic refrigeration technologies face environmental concerns due to the use of freon gases and high costs associated with rare earth elements, with existing magnetic materials exhibiting either narrow operating temperature ranges or low magnetic entropy changes.
Innovation Solution
Development of magnetic materials with compositions represented by general formulas (R11−yR2)yFe100−x and (R1−yX)yFe100−x, incorporating Th2Zn17, Th2Ni17, or TbCu7 crystal phases, utilizing a combination of rare earth elements and iron to achieve second-order magnetic phase transitions at room temperature with reduced magnetic anisotropy and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If first order magnetic phase transition materials (Gd5(Ge, Si)4, La(Fe, Si)13, Mn—As—Sb) are used, then large entropy change can be obtained with low magnetic field, but operating temperature range becomes narrow
Solution Approach 1:
The patent uses composite materials by combining rare earth elements (Sm, Er with Ce, Pr, Nd, Tb, Dy) in specific ratios within the Th2Zn17, Th2Ni17, or TbCu7 crystal phase structures. This composite approach allows the material to exhibit second-order magnetic phase transitions with both large entropy changes and wide operating temperature ranges, resolving the contradiction between entropy change magnitude and temperature range adaptability.
2Adaptability or versatility
If rare earth elements (Gd, Y, Dy) or rare earth alloys are used, then wide operating temperature range and large entropy change are achieved, but material cost becomes high
Solution Approach 1:
The patent changes the compositional parameters by using specific rare earth element combinations (Sm, Er with Ce, Pr, Nd, Tb, Dy) in controlled ratios (x and y parameters in the general formula) within Th2Zn17, Th2Ni17, or TbCu7 crystal phases. This parameter optimization maintains the desired magnetic properties and wide temperature range while reducing dependence on expensive rare earth elements like Gd, Y, and Dy, thereby lowering material cost.
3Ease of manufacture
If (Ce, Y)2Fe17 based magnetic material is used, then cost is reduced and wide temperature range is achieved, but magnetic entropy change amount becomes small due to high magnetic anisotropy
Solution Approach 1:
The patent applies local quality by creating specific local environments for rare earth elements within the Th2Zn17, Th2Ni17, or TbCu7 crystal phase structures. By positioning Sm and Er atoms in specific lattice sites alongside Ce, Pr, Nd, Tb, or Dy atoms, the material achieves reduced magnetic anisotropy locally, enabling large magnetic entropy changes while maintaining cost-effectiveness and wide temperature range operation.
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 materials provide a high-performance magnetic refrigeration solution with large magnetic entropy changes at low magnetic fields and near-room temperature Curie temperatures, offering a cost-effective and environmentally friendly alternative.
Implementation Method 1
The magnetic refrigeration technologies use the magnetocaloric effect of magnetic material instead of freon gases or substitute freon gases as a refrigerant to realize a refrigeration cycle
Implementation Method 2
the refrigeration cycle is realized by using a magnetic entropy change (ΔS) of the magnetic material associated with a magnetic phase transition (phase transition between a paramagnetic state and a ferromagnetic state)
Data Source
AI summary
Magnetic materials, having: a composition represented by a general formula:(R1−yXy)x(Fe1−aMa)100−xwhere, R is at least one of element selected from the group consisting of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Y, X is at least one of element selected from the group consisting of Ti, Zr and Hf, M is at least one of element selected from the group consisting of V, Cr, Mn, Ni, Cu, Zn, Nb, Mo, Ta, W, Al, Si, Ga and Ge, x is a value satisfying 4≦x≦20 atomic %, y is a value satisfying 0.01≦y≦0.9, and a is a value satisfying 0≦a≦0.2, wherein the magnetic material includes a Th2Ni17 crystal phase or a TbCu7 crystal phase as a main phase, that are useful for magnetic refrigeration.