<i>Ab initio</i>
 phase stabilities of Ce-based hard magnetic materials and comparison with experimental phase diagrams

Sözen, Halil Ibrahim; Ener, Semih; Maccari, Fernando; Skokov, Konstantin P.; Gutfleisch, Oliver; Körmann, Fritz; Neugebauer, Jörg; Hickel, Tilmann

doi:10.1103/physrevmaterials.3.084407

Cited by 27 publications

(16 citation statements)

References 86 publications

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“…In experimental investigations, the CeFe 11 Ti phase was only observed at high temperatures above 1000 K. Below this temperature, only the phases C15 CeFe 2 and Ce 2 Fe 17 were detected. This is confirmed by ab initio free-energy calculations, which reveal that the presence of the CeFe 2 Laves phase suppresses the formation of CeFe 11 Ti up to 700 K [596,597]. In Ce-based Ce-Fe-B alloys containing hard-magnetic Ce 2 Fe 14 B, partial substitution of Ce by La was found to suppress the Laves phase CeFe 2 and to promote the formation of (Ce,La) 2 Fe 14 B with increased saturation magnetization and Curie temperature [598].…”

Section: Hard Magnetic Applicationssupporting

confidence: 58%

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

2020

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Laves phases with their comparably simple crystal structure are very common intermetallic phases and can be formed from element combinations all over the periodic table resulting in a huge number of known examples. Even though this type of phases is known for almost 100 years, and although a lot of information on stability, structure, and properties has accumulated especially during the last about 20 years, systematic evaluation and rationalization of this information in particular as a function of the involved elements is often lacking. It is one of the two main goals of this review to summarize the knowledge for some selected respective topics with a certain focus on non-stoichiometric, i.e., non-ideal Laves phases. The second, central goal of the review is to give a systematic overview about the role of Laves phases in all kinds of materials for functional and structural applications. There is a surprisingly broad range of successful utilization of Laves phases in functional applications comprising Laves phases as hydrogen storage material (Hydraloy), as magneto-mechanical sensors and actuators (Terfenol), or for wear- and corrosion-resistant coatings in corrosive atmospheres and at high temperatures (Tribaloy), to name but a few. Regarding structural applications, there is a renewed interest in using Laves phases for creep-strengthening of high-temperature steels and new respective alloy design concepts were developed and successfully tested. Apart from steels, Laves phases also occur in various other kinds of structural materials sometimes effectively improving properties, but often also acting in a detrimental way.

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Section: Hard Magnetic Applicationssupporting

confidence: 58%

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

2020

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“…This FM state is characterized by local moments of 2. 58 for the Fe 6c site, 2.04-2.08 for the Fe 9d site, 2.38-2.41 for the Fe 18f site, 2.20-2.21 for the Fe 18h site, and -0.80 for the Ce 6c site, which are in accordance with the other theoretical works that employed the GGA functional [6,28]. Again, the Fe (6c) atoms provide the largest moment also for this calculation.…”

Section: Ground State With Dftsupporting

confidence: 90%

“…The same overestimation was obtained in Ref. [28] for a plain DFT/GGA calculations using the VASP code [29,30,31,32] and the Projector Augmented Wave (PAW) [33] method. All above mentioned studies assumed a collinear FM ground state.…”

Section: T C T T T Nsupporting

confidence: 82%

Ab-initio study of the electronic structure and magnetic properties of Ce$_2$Fe$_{17}$

Vishina,

Eriksson,

Vekilova

et al. 2022

Preprint

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The Ce 2 Fe 17 intermetallic compound has been studied intensely for several decades; its low-temperature state is reported experimentally either as ferromagnetic or antiferromagnetic by different authors, with a measured ordering temperature ranging within a hundred Kelvin. The existing theoretical investigations overestimate the experimental total magnetic moment of Ce 2 Fe 17 by 20-40 % and predict a ferromagnetic ground state. By means of first-principle electronic structure calculations, we show that the total magnetic moment of Ce 2 Fe 17 can be reproduced within the Local Density Approximation while functionals based on the Generalized Gradient Approximation fail. Atomistic spin dynamics simulations are shown to capture the change in the magnetic state of Ce 2 Fe 17 with temperature, and closely replicate the reported helical structure that appears in some of the experimental investigations.

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“…Available resources of heavy rare earths are scarce, thus motivating efforts to replace heavy rare-earth intermetallics with so-called rare-earth balance magnets 2 containing more abundant rare-earth elements, in particular Ce 1,[4][5][6][7] . A significant limitation to the magnetic hardness of Ce-transition metal intermetallics is caused by the well-known tendency of Ce-4f electrons to form heavy-electron itinerant bands, as for instance observed in socalled "heavy-fermion" compounds 8 .…”

Section: Introductionmentioning

confidence: 99%

“…We focus on the Ce-Fe "1-12" material system 4,7,17,20,21 , which has recently been under scrutiny as a potential hard magnet 16,22,23 . Our calculations show a significant reduction of the Ce magnetic moment due to the Kondo effect.…”

Section: Introductionmentioning

confidence: 99%

Intrinsically weak magnetic anisotropy of cerium in potential hard-magnetic intermetallics

et al. 2021

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Cerium-based intermetallics are currently attracting much interest as a possible alternative to existing high-performance magnets containing scarce heavy rare-earth elements. However, the intrinsic magnetic properties of Ce in these systems are poorly understood due to the difficulty of a quantitative description of the Kondo effect, a many-body phenomenon where conduction electrons screen out the Ce-4f moment. Here, we show that the Ce-4f shell in Ce–Fe intermetallics is partially Kondo screened. The Kondo scale is dramatically enhanced by nitrogen interstitials suppressing the Ce-4f contribution to the magnetic anisotropy, in striking contrast to the effect of nitrogenation in isostructural intermetallics containing other rare-earth elements. We determine the full temperature dependence of the Ce-4f single-ion anisotropy and show that even unscreened Ce-4f moments contribute little to the room-temperature intrinsic magnetic hardness. Our study thus establishes fundamental constraints on the potential of cerium-based permanent magnet intermetallics.

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Ab initio phase stabilities of Ce-based hard magnetic materials and comparison with experimental phase diagrams

Cited by 27 publications

References 86 publications

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

Ab-initio study of the electronic structure and magnetic properties of Ce$_2$Fe$_{17}$

Intrinsically weak magnetic anisotropy of cerium in potential hard-magnetic intermetallics

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