R-Fe Magnetic Refrigeration Material for Wide-Range Entropy Change
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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 (R1-yR2)xFe100-x and (R1-yX)yFe100-x, incorporating Th2Zn17, Th2Ni17, or TbCu7 crystal phases, utilizing a combination of rare earth elements and iron to achieve a second-order magnetic phase transition at a lower cost and near-room temperature magnetocaloric effect.
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, Ce, Pr, Nd, Tb, Dy) with iron in specific ratios to create R-Fe based materials. This composite approach allows achieving both large entropy change and wide operating temperature range through controlled composition, resolving the contradiction between entropy change magnitude and temperature range adaptability.
Solution Approach 2:
The patent applies parameter changes by systematically varying the composition parameters (x and y in the formula (R1, R2)xCa100-x) and crystal structure parameters to optimize both the entropy change and Curie temperature. By adjusting rare earth element ratios and atomic percentages, the material achieves large magnetic entropy change while maintaining wide operating temperature range through parameter optimization.
2Adaptability or versatility
If rare earth elements (Gd, Y, Dy) or their alloys are used, then wide operating temperature range and large entropy change are achieved, but material cost becomes high
Solution Approach 1:
The patent replaces expensive rare earth elements with more cost-effective alternatives by using R-Fe based materials where R includes elements like Ce, Pr, Nd, and combinations with Ca. This substitution maintains the desired magnetic properties and wide operating temperature range while significantly reducing material cost, embodying the principle of using cheaper materials that still achieve the required performance.
Solution Approach 2:
The patent optimizes composition parameters (atomic percentages of rare earth elements and iron) to achieve the desired magnetic properties at lower costs. By carefully controlling the ratios of rare earth elements to iron and optimizing the overall composition, the material maintains wide operating temperature range and adequate entropy change while reducing dependence on expensive rare earth content.
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 addresses the low magnetic entropy change issue by changing composition parameters - using specific ratios of rare earth elements (Sm, Er, Ce, Pr, Nd, Tb, Dy) with iron in the (R1, R2)xCa100-x formula. By optimizing these compositional parameters and controlling the crystal structure, the material achieves both cost-effectiveness and adequate magnetic entropy change, overcoming the limitation of (Ce, Y)2Fe17 based materials.
Solution Approach 2:
The patent uses composite materials by combining multiple rare earth elements with iron in specific proportions. This composite R-Fe material structure allows achieving better magnetic entropy change compared to simple (Ce, Y)2Fe17 compounds while maintaining cost-effectiveness, as the synergistic combination of different rare earth elements compensates for the high magnetic anisotropy issue.
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 proposed magnetic materials exhibit a large magnetic entropy change at a relatively low magnetic field, operating within a wide temperature range, and are cost-effective, suitable for use in magnetic refrigeration devices while minimizing environmental impact.
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. Specifically, 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
A magnetic material for magnetic refrigeration has a composition represented by (R11-yR2y)xFe100-x (R1 is at least one of element selected from Sm and Er, R2 is at least one of element selected from Ce, Pr, Nd, Tb and Dy, and x and y are numerical values satisfying 4≦x≦20 atomic % and 0.05≦y≦0.95), and includes a Th2Zn17 crystal phase, a Th2Ni17 crystal phase, or a TbCu7 crystal phase as a main phase.