Influence of the Magnetic Anisotropy on the Magnetic Entropy Change of Ni2Mn(Ga, Bi) Memory Shape Alloy

abstract

The magnetocaloric effect (MCE) is a good chance to create a more efficient refrigeration technique, both in energy and environmental friendliness. On the search for materials with large MCE (mainly characterized by a great magnetic entropy variation) in a wide temperature range around room temperature, this work focuses on the widely studied Hensler alloy and the influence of bismuth alloying in the stoichiometry Ni2MnGa in an attempt to make the magnetic and structural transition temperatures, T-C and T-M, come closer, and therefore create a large MCE. In addition, we discuss the influence of alloying processes on the magnetic anisotropy. Our results have in fact increased T-M and decreased T-C, but Bi substitution in Ga site (from 0 up to 5%) has been insufficient to merge those two transitions. The maximum magnetic entropy change was found to be 3.8 J/kg.K for the pure sample (without Bi) and 2.2 J/kg.K for sample 4 (maximum Bi concentration).

keywords

PHASE-TRANSITIONS; TEMPERATURES; ABSOLUTE

subject category

Engineering; Physics

authors

Leitao, JCV; Rocco, DL; Amaral, JS; Reis, MD; Amaral, VBS; Fernandes, RP; Martins, NV; Tavares, PB

our authors

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