Rare-earth-free Fe2P-based compounds: Tuning and modeling of hard magnetic properties
Abstract
Fe2−xCoxP1−ySiy has attracted significant attention for permanent magnet applications due to its promising intrinsic magnetic properties and the absence of strategic elements such as rare earths. To date, most samples reported in the literature are polycrystalline and obtained via mechanical alloying, which makes direct measurement of magnetocrystalline anisotropy particularly challenging. In contrast, only a limited number of single-crystal compositions have been investigated. In this work, Fe2−xCoxP1−ySiy polycrystalline samples were synthesized by combined induction and arc melting techniques. Compared with mechanically alloyed materials reported in the literature, the resulting samples exhibit a higher degree of phase purity, with secondary phases appearing only in specimens with high Si content. The composition dependence of the intrinsic magnetic properties, namely Curie temperature, saturation magnetization, and magnetocrystalline anisotropy, was systematically investigated over the compositional range 0.1≤x≤0.3 and 0.1≤y≤0.4, extending beyond the range previously explored in single crystals. The anisotropy field was directly measured on polycrystalline samples by means of the Singular Point Detection technique in pulsed magnetic fields. The maximum anisotropy field μ0HA=2.84 T was found for Fe1.90Co0.10P0.80Si0.20, which also exhibits a saturation magnetization MS=111 A m2/kg and a Curie temperature TC=495 K. All investigated compounds display a magnetic hardness parameter κ>1 and tunable intrinsic magnetic properties. The theoretical maximum energy product approaches 200 kJ/m comparable to values obtained for single crystals. These characteristics, together with the possibility of obtaining nearly single-phase materials through scalable melting routes, make this compound family one of the most promising candidates for rare-earth-free permanent magnets with performance intermediate between ferrites and rare-earth magnets. Experimental results were complemented by density functional theory calculations, which were used to map the magnetic moment and magnetocrystalline anisotropy energy over a broader compositional space. The calculations reveal that band filling plays a crucial role in optimizing the anisotropy and overall magnetic performance of the Fe2−xCoxP1−ySiy system.
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BibTeX
@article{casadei2026rareearthfree,
title = {{Rare-earth-free Fe2P-based compounds: Tuning and modeling of hard magnetic properties}},
author = {Matteo Casadei and Mirosław Werwiński and Matteo Belli and Francesco Cugini and Giovanna Trevisi and Simone Fabbrici and Riccardo Cabassi and Giuseppe Allodi and Riccardo Pagnoni and César de Julián Fernández and Massimo Solzi and Vincent Fournée and Isabella Gallino and Ralf Busch and Samuele Sanna and Franca Albertini},
journal = {Acta Materialia},
year = {2026},
month = sep,
doi = {10.1016/j.actamat.2026.122802},
url = {https://hal.science/hal-05838100v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Rare-earth-free Fe2P-based compounds: Tuning and modeling of hard magnetic properties
AU - Matteo Casadei
AU - Mirosław Werwiński
AU - Matteo Belli
AU - Francesco Cugini
AU - Giovanna Trevisi
AU - Simone Fabbrici
AU - Riccardo Cabassi
AU - Giuseppe Allodi
AU - Riccardo Pagnoni
AU - César de Julián Fernández
AU - Massimo Solzi
AU - Vincent Fournée
AU - Isabella Gallino
AU - Ralf Busch
AU - Samuele Sanna
AU - Franca Albertini
PY - 2026
DA - 2026/09/26
JO - Acta Materialia
DO - 10.1016/j.actamat.2026.122802
UR - https://hal.science/hal-05838100v1
AB - Fe2−xCoxP1−ySiy has attracted significant attention for permanent magnet applications due to its promising intrinsic magnetic properties and the absence of strategic elements such as rare earths. To date, most samples reported in the literature are polycrystalline and obtained via mechanical alloying, which makes direct measurement of magnetocrystalline anisotropy particularly challenging. In contrast, only a limited number of single-crystal compositions have been investigated. In this work, Fe2−xCoxP1−ySiy polycrystalline samples were synthesized by combined induction and arc melting techniques. Compared with mechanically alloyed materials reported in the literature, the resulting samples exhibit a higher degree of phase purity, with secondary phases appearing only in specimens with high Si content. The composition dependence of the intrinsic magnetic properties, namely Curie temperature, saturation magnetization, and magnetocrystalline anisotropy, was systematically investigated over the compositional range 0.1≤x≤0.3 and 0.1≤y≤0.4, extending beyond the range previously explored in single crystals. The anisotropy field was directly measured on polycrystalline samples by means of the Singular Point Detection technique in pulsed magnetic fields. The maximum anisotropy field μ0HA=2.84 T was found for Fe1.90Co0.10P0.80Si0.20, which also exhibits a saturation magnetization MS=111 A m2/kg and a Curie temperature TC=495 K. All investigated compounds display a magnetic hardness parameter κ>1 and tunable intrinsic magnetic properties. The theoretical maximum energy product approaches 200 kJ/m comparable to values obtained for single crystals. These characteristics, together with the possibility of obtaining nearly single-phase materials through scalable melting routes, make this compound family one of the most promising candidates for rare-earth-free permanent magnets with performance intermediate between ferrites and rare-earth magnets. Experimental results were complemented by density functional theory calculations, which were used to map the magnetic moment and magnetocrystalline anisotropy energy over a broader compositional space. The calculations reveal that band filling plays a crucial role in optimizing the anisotropy and overall magnetic performance of the Fe2−xCoxP1−ySiy system.
SN - 1359-6454
ER -