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Colossal heating efficiency via eddy currents in amorphous microwires with nearly zero magnetostriction
Irene Morales1, Diego Archilla1, Patricia de la Presa2,3
1Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, A6 22,500 Km, 20230, Las Rozas, Spain.
Scientific Reports
|January 19, 2020
Summary
Magnetic microwires exhibit exceptionally high heating efficiency, far exceeding magnetic nanoparticles. This is attributed to induced eddy currents, making them promising for low-cost inductive heating applications.
Area of Science:
- Materials Science
- Physics
- Nanotechnology
Background:
- Magnetic nanoparticles' heating efficiency is linked to hysteresis losses.
- Microwires (MWs) exhibit non-coherent magnetic reversal, suggesting lower heating efficiency than nanoparticles.
- However, microwires demonstrate unexpectedly high heating efficiencies.
Purpose of the Study:
- Investigate the mechanism behind the colossal heating efficiency observed in magnetic microwires.
- Determine the factors influencing heating efficiency in microwires under radiofrequency fields.
- Assess the potential of microwires for inductive heating applications.
Main Methods:
- Experimental analysis of microwire heating efficiency under radiofrequency fields.
- Measurement of heating efficiency (W/g) as a function of microwire length and quantity.
- Characterization of microwire properties, including magnetostrictive constant and domain structure.
Main Results:
- Colossal heating efficiencies of 1000–2800 W/g were observed in microwires at low magnetic fields (36 Oe) and radiofrequencies (625 kHz).
- The heating mechanism is inferred to be the Joule effect from eddy currents induced by the magnetic field.
- Optimal heating was observed in Fe2.25Co72.75Si10B15 microwires (30 μm diameter, 5 mm length) with near-zero magnetostriction and axial inner core domains.
- High heating was achieved with only 24 W of supplied power.
Conclusions:
- The colossal heating in microwires is primarily due to Joule heating from eddy currents, not hysteresis losses.
- Microwires with specific properties (near-zero magnetostriction, axial domains) offer superior inductive heating performance.
- These findings highlight the potential of magnetic microwires for energy-efficient inductive heating applications.
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