The Magnetocaloric Effect of Some Rare Earth Metals
The Navy is investigating a reciprocating magnetic refrigeration concept that uses an active regenerator. The geometry of this active regenerator is an embossed ribbon configured of a formable material (generally a rare earth metal) having a reasonably large magnetocaloric effect at its Neel or Curie temperature. Several rare earths have shown large increases in heat capacity at their respective transition temperatures. Samples of two rare earth metals, terbium and holmium, were subjected to a 7-tesla change in magnetic field over a range of temperatures and the adiabatic temperature change measured. Results indicated a 10.3-°C temperature change in terbium at 237 K and a 6.1-°C change in holmium at 136 K. In addition, no thermal hysteresis effect was observed in these materials near their Neel temperatures.
KeywordsEuropium Helium Gadolinium Flange Liquefaction
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