Magnetocaloric effect in dysprosium
The magnetocaloric effect in polycrystalline Dy was measured between 84 and 280 K in measuring fields from 1 to 7 T. These adiabatic temperature changes reflect structural changes in Dy with applied field and temperature, and include the first magnetocaloric data for a helical antiferromagnet. These measurements were made to evaluate Dy as working material in magnetic refrigeration applications. Above T/sub N/ (179 K) a field increase always causes heating; below T/sub N/ fields less than about 2 T cause cooling for some values of initial temperature. The largest temperature increase with a 7 T field occurs at the Neel point (triangle-openT=11.5 K), and at fields below 2 T near the Curie point (triangle-openT=2 K at 100 K). For refrigeration purposes, the optimal working region for a Dy cooling element is field dependent. This Dy data suggests that, because of complex magnetic structure changes, antiferromagnetic rare earths may be useful for refrigeration over a broad temperature range near T/sub N/ at very high fields, and may be preferable to ferromagnetic materials over certain restricted temperature regions above the Curie point in low fields produced by permanent magnets (< or =1 T).
- Research Organization:
- NASA Lewis Research Center, Cleveland, Ohio
- OSTI ID:
- 6298920
- Journal Information:
- J. Appl. Phys.; (United States), Vol. 50:B3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DYSPROSIUM
MAGNETO-THERMAL EFFECTS
ANTIFERROMAGNETISM
CURIE POINT
NEEL TEMPERATURE
PHASE TRANSFORMATIONS
POLYCRYSTALS
REFRIGERATION
TEMPERATURE DEPENDENCE
COOLING
CRYSTALS
ELEMENTS
MAGNETISM
METALS
PHYSICAL PROPERTIES
RARE EARTHS
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
360102* - Metals & Alloys- Structure & Phase Studies