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Document IIF

Échec de la relation de Maxwell pour la quantification des effets caloriques dans des matériaux ferroïques.

Failure of the Maxwell relation for the quantification of caloric effects in ferroic materials.

Numéro : sect. 2

Auteurs : NIEMANN R., HECZKO O., SCHULTZ L., et al.

Résumé

Giant caloric effects were reported in elasto-, electro- and magnetocaloric materials near phase transformations. Commonly, their entropy change is indirectly evaluated by a Maxwell relation. The authors report the fundamental failure of this approach and they analyze exemplarily the Ni-Mn-Ga magnetic shape memory alloy. An applied field results in magnetically induced reorientation of martensitic variants, which form during the phase transformation. This results in a spurious magnetocaloric effect, which only disappears when repeating the measurement. This failure is universal as the vector character of the applied field is not considered in the common scalar evaluation of a Maxwell relation.

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Pages : 219-226

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Détails

  • Titre original : Failure of the Maxwell relation for the quantification of caloric effects in ferroic materials.
  • Identifiant de la fiche : 30005540
  • Langues : Anglais
  • Source : 5th International Conference on Magnetic Refrigeration at Room Temperature (Thermag V). Proceedings: Grenoble, France, September 17-20, 2012.
  • Date d'édition : 17/09/2012

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