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Updated: Jul 5, 2025
07:03
Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
8.8K
Giant Low-Field Cryogenic Magnetocaloric Effect in a Polycrystalline EuB4O7 Compound
Yuanpeng Wang1,2, Junsen Xiang3, Lei Zhang2
1School of Rare earths, University of Science and Technology of China, Hefei 230026, People's Republic of China.
Journal of the American Chemical Society
|January 23, 2024
Summary
EuB4O7 demonstrates superior cooling performance as an alternative to helium-3 refrigeration. This compound achieves lower temperatures and longer cooling times, making it promising for adiabatic demagnetization refrigeration.
Area of Science:
- Materials Science
- Thermodynamics
- Condensed Matter Physics
Background:
- Helium-3 resources are scarce and expensive, driving the search for alternative refrigeration technologies.
- Adiabatic demagnetization refrigeration (ADR) is a promising alternative for achieving ultralow temperatures.
Purpose of the Study:
- Investigate the magnetism and magnetocaloric effect (MCE) of EuB4O7 for ADR applications.
- Evaluate EuB4O7 as a potential refrigerant to overcome helium-3 limitations.
Main Methods:
- Magnetic measurements to understand magnetic ordering.
- Quasi-adiabatic demagnetization measurements to assess cooling performance.
- Analysis of magnetic entropy change at various magnetic field strengths.
Main Results:
- EuB4O7 shows no magnetic order above 0.4 K, with dipolar interactions around 800 mK.
- Maximum magnetic entropy change reached up to 47.6 J·kg-1·K-1 at 50 kOe.
- Achieved a lowest temperature of 289 mK, outperforming commercial Gd3Ga5O12 (GGG) refrigerant.
- Sustained cooling below 700 mK for over 70 minutes at a 2 K environment.
Conclusions:
- EuB4O7 exhibits significant magnetocaloric effect and superior cooling capabilities.
- This compound is a viable and high-performance alternative to helium-3 for ADR.
- Further research into EuB4O7 can advance ultralow-temperature refrigeration technologies.
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