This work presents a top-down method, based on ball-milling techniques, for the preparation of and micro-meter and sub-micro-meter sized particles. The structural, morphological, and magnetic features of the as-milled and annealed particles are investigated. First, we observe a detrimental effect on the magnetic properties and magneto-structural phase transitions of the induced lattice defects and atomic disorder, and second, we demonstrate the possibility to recover the original configuration by subsequent annealing. The optimization of the latter is strongly dependent on the initial milling energy, but, generally, a fast recovery of the Heusler and martensitic phases is observed. Further, we can tune the transformation temperatures or even improve the magnetic properties, in terms of increase of phase homogeneity, decrease of thermal hysteresis and increase of saturation magnetization, by decreasing the particles' size of the examined compounds.

Multifunctional Ni-Mn-Ga and Ni-Mn-Cu-Ga Heusler particles towards the nanoscale by ball-milling technique

Davide Delmonte;Giovanna Trevisi;Lucia Nasi;Franca Albertini
2021

Abstract

This work presents a top-down method, based on ball-milling techniques, for the preparation of and micro-meter and sub-micro-meter sized particles. The structural, morphological, and magnetic features of the as-milled and annealed particles are investigated. First, we observe a detrimental effect on the magnetic properties and magneto-structural phase transitions of the induced lattice defects and atomic disorder, and second, we demonstrate the possibility to recover the original configuration by subsequent annealing. The optimization of the latter is strongly dependent on the initial milling energy, but, generally, a fast recovery of the Heusler and martensitic phases is observed. Further, we can tune the transformation temperatures or even improve the magnetic properties, in terms of increase of phase homogeneity, decrease of thermal hysteresis and increase of saturation magnetization, by decreasing the particles' size of the examined compounds.
2021
Istituto dei Materiali per l'Elettronica ed il Magnetismo - IMEM
Heusler alloysMartensitic transformationMechanical millingMagnetic propertiesMagnetic nanoparticles
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/400462
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