Utilization of the Magnetic Entropy in Active Magnetic Regenerator Materials
The magnetic entropy associated with magnetic ordering has been determined for ~20 lanthanide materials and it varies from ~60 to ~90% of the theoretical Rln (2J+l) value. The utilization of this entropy in the magnetocaloric effect (MCE) for a 0 to 7.5 T field change, however, is much less, ranging from ~10 to ~30% at the Curie temperature (TC) for the 23 materials studied. At TC+100K the MCE is found to saturate and the magnetic entropy utilization increases up to ~20 to ~50%. These data indicate that lattice contribution to the heat capacity plays an important role in the magnetocaloric effect.
KeywordsHeat Capacity Curie Temperature Magnetocaloric Effect Magnetic Entropy Change Magnetic Refrigerant
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- 4.K.A. Gschneidner, Jr., V.K. Pecharsky, and S.K. Malik, Paper No. TU-Z3–4, Presented at Intern. Cryogenic Materials Conference, Columbus, OH (July 18–21, 1995).Google Scholar