On the correct estimation of the magnetic entropy change across the magneto-structural transition from the Maxwell relation: Study of MnCoGeBX alloy ribbons


Quintana-Nedelcos A., Sanchez Llamazares J. L., Sanchez-Valdes C. F., Alvarez Alonso P., Gorria P., Shamba P., ...Daha Fazla

JOURNAL OF ALLOYS AND COMPOUNDS, cilt.694, ss.1189-1195, 2017 (SCI-Expanded) identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 694
  • Basım Tarihi: 2017
  • Doi Numarası: 10.1016/j.jallcom.2016.10.116
  • Dergi Adı: JOURNAL OF ALLOYS AND COMPOUNDS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.1189-1195
  • Anahtar Kelimeler: First order magnetocaloric effect, Maxwell relation applicability, Magnetic entropy change, Refrigerant capacity, MnCoGeBx alloys, MARTENSITIC-TRANSFORMATION, MAGNETOCALORIC PROPERTIES, SIZE
  • Marmara Üniversitesi Adresli: Evet

Özet

An accurate calculation of the different magnetocaloric-related magnitudes derived from the temperature dependence of the magnetic entropy change in materials exhibiting first-order magnetocaloric effect is imperative to correctly estimate the true potential of a specific material for refrigeration purposes. In this contribution, we present a meticulous study of two different thermal procedures to measure the set of isothermal magnetization curves from which the total field induced magnetic entropy change, Delta S-T, is calculated using the adequate Maxwell relation. If the accurate determination of Delta S-T for any temperature is pursued the thermal and magnetic history of the materials must be taken into account, and then, the unidirectional measurement of reversible isothermal magnetization curves after a thermal cycle is required. The analysis was conducted on MnCoGeB0.01 alloy ribbons that show a giant Delta S-T at the coupled magneto-structural transition, from a ferromagnetic (TiNiSi-type) phase to a paramagnetic (NiIn2-type) one, owing to the concomitant abrupt magnetization change. We suggest that the conclusions reached can be applicable to any other system displaying magnetocaloric effect originated at a first order phase transition. (C) 2016 Elsevier B.V. All rights reserved.