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Entropy change and kinetic effects at the magnetostructural phase transition of MnBi / Vittorio Basso in International journal of refrigeration, Vol. 37 N° 1 (Janvier 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 266–272 Titre : Entropy change and kinetic effects at the magnetostructural phase transition of MnBi Titre original : Changement d'entropie et effets cinétiques à la transition de phase magnétostructurelle de MnBi Type de document : texte imprimé Auteurs : Vittorio Basso, Auteur ; Elena Sonia Olivetti, Auteur ; Luca Martino, Auteur Année de publication : 2014 Article en page(s) : pp. 266–272 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Magnetocaloric  effect;  MnBi;  kinetic  effects;  first  order  phase  transition Résumé : In this paper we investigate the entropy change and the kinetics at the magneto-structural transition (at 628 K) of polycrystalline MnBi. Samples were prepared by rapid quenching and annealing and exhibit 86 wt% of the hexagonal MnBi phase. The entropy change at the transition is found to be Δs = 17.6 J kg−1 K−1 and the magnetic field shifts the transition temperature at a rate of 2.6 K T−1. The temperature hysteresis, of 19 K, is quite large for magneto-thermal application. The transition shows kinetics effects upon cooling in which the transition temperature is found to depend approximately to the logarithm of the temperature rate with coefficient −3.8 K. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001783 [article] Entropy change and kinetic effects at the magnetostructural phase transition of MnBi = Changement d'entropie et effets cinétiques à la transition de phase magnétostructurelle de MnBi [texte imprimé] / Vittorio Basso, Auteur ; Elena Sonia Olivetti, Auteur ; Luca Martino, Auteur . - 2014 . - pp. 266–272. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 266–272 Mots-clés : Magnetocaloric  effect;  MnBi;  kinetic  effects;  first  order  phase  transition Résumé : In this paper we investigate the entropy change and the kinetics at the magneto-structural transition (at 628 K) of polycrystalline MnBi. Samples were prepared by rapid quenching and annealing and exhibit 86 wt% of the hexagonal MnBi phase. The entropy change at the transition is found to be Δs = 17.6 J kg−1 K−1 and the magnetic field shifts the transition temperature at a rate of 2.6 K T−1. The temperature hysteresis, of 19 K, is quite large for magneto-thermal application. The transition shows kinetics effects upon cooling in which the transition temperature is found to depend approximately to the logarithm of the temperature rate with coefficient −3.8 K. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001783

Entropy change at magnetic phase transitions of the first order and second order / Vittorio Basso in International journal of refrigeration, Vol. 37 N° 1 (Janvier 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 257-265 Titre : Entropy change at magnetic phase transitions of the first order and second order Titre original : Changement d'entropie et transitions de la phase magnétique de premier et de second ordre Type de document : texte imprimé Auteurs : Vittorio Basso, Auteur ; Carlo P. Sasso, Auteur ; Michaela Küpferling, Auteur Année de publication : 2014 Article en page(s) : pp. 257-265 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Magnetocaloric  effect;  Gd;  La(Fe–Si)13;  Heusler  alloy  Ni–Mn–Co–Sn;  mean  field  theory Résumé : Magnetocaloric properties close to first order and second order phase transitions are presented and discussed. The specific heat capacity as a function of the magnetic field and the magnetic field induced entropy change has been measured by direct heat flux calorimetry in Gd, hydrogenated La(Fe–Mn–Si)13, La(Fe–Co–Si)13 and the Heusler alloy Ni–Mn–Co–Sn. The resulting s(Ha,T) entropy constitutive relation is compared with a model including the ferromagnetic, electronic and structural contributions to the free energy. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001990 [article] Entropy change at magnetic phase transitions of the first order and second order = Changement d'entropie et transitions de la phase magnétique de premier et de second ordre [texte imprimé] / Vittorio Basso, Auteur ; Carlo P. Sasso, Auteur ; Michaela Küpferling, Auteur . - 2014 . - pp. 257-265. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 37 N° 1 (Janvier 2014) . - pp. 257-265 Mots-clés : Magnetocaloric  effect;  Gd;  La(Fe–Si)13;  Heusler  alloy  Ni–Mn–Co–Sn;  mean  field  theory Résumé : Magnetocaloric properties close to first order and second order phase transitions are presented and discussed. The specific heat capacity as a function of the magnetic field and the magnetic field induced entropy change has been measured by direct heat flux calorimetry in Gd, hydrogenated La(Fe–Mn–Si)13, La(Fe–Co–Si)13 and the Heusler alloy Ni–Mn–Co–Sn. The resulting s(Ha,T) entropy constitutive relation is compared with a model including the ferromagnetic, electronic and structural contributions to the free energy. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001990