Thermal decomposition of ThMn12-type phase and its optimum stabilizing elements in SmFe12-based alloys

Dirba, Imants; Harashima, Yosuke; Sepehri-Amin, H.; Ohkubo, T.; Miyake, Takashi; Hirosawa, S.; Hono, K.

doi:10.1016/j.jallcom.2019.152224

Cited by 54 publications

(13 citation statements)

References 31 publications

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“…Using first-principle calculations, Dirba et al [ 113 ] determined the formation energy and magnetic moments for the three inequivalent sites

and

in the SmFe

, for various M elements. The formation energy was calculated as follow:

…”

Section: Intrinsic Magnetic Propertiesmentioning

confidence: 99%

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Structure and Magnetic Properties of Intermetallic Rare-Earth-Transition-Metal Compounds: A Review

Bessaïs

2021

Materials

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This review discusses the properties of candidate compounds for semi-hard and hard magnetic applications. Their general formula is R1−sT5+2s with R = rare earth, T = transition metal and 0≤s≤0.5 and among them, the focus will be on the ThMn12- and Th2Zn17-type structures. Not only will the influence of the structure on the magnetic properties be shown, but also the influence of various R and T elements on the intrinsic magnetic properties will be discussed (R = Y, Pr, Nd, Sm, Gd, … and T = Fe, Co, Si, Al, Ga, Mo, Zr, Cr, Ti, V, …). The influence of the microstructure on the extrinsic magnetic properties of these R–T based intermetallic nanomaterials, prepared by high energy ball milling followed by short annealing, will be also be shown. In addition, the electronic structure studied by DFT will be presented and compared to the results of experimental magnetic measurements as well as the hyperfine parameter determined by Mössbauer spectrometry.

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“…Using first-principle calculations, Dirba et al [ 113 ] determined the formation energy and magnetic moments for the three inequivalent sites

and

in the SmFe

, for various M elements. The formation energy was calculated as follow:

…”

Section: Intrinsic Magnetic Propertiesmentioning

confidence: 99%

“… Calculated formation energy for SmFe

( M = Ti, V, Co, Cu, Ga) [ 113 ]. The magenta dashed line corresponds to formation energy of the hypothetical SmFe

energy.…”

Section: Figurementioning

confidence: 99%

Structure and Magnetic Properties of Intermetallic Rare-Earth-Transition-Metal Compounds: A Review

Bessaïs

2021

Materials

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“…In contrast, the situation in SmFe -based magnets [ 31 , 32 ] is not the case: such a suitable liquid phase possible to coexist with SmFe is yet to be established [ 33 ]. Depending on the composition, the primary intergranular subphase of SmFe -based magnets becomes unfavorably bcc Fe [ 34 ]. Another possibility for the intergranular subphase is SmCu, as we examine the Gibbs free energy for Sm-Fe-Cu ternary systems combining the CALPHAD approach with first-principles calculations.…”

Section: Interfaces Between the Main Phase And An Intergranular Phasementioning

confidence: 99%

First-principles determination of intergranular atomic arrangements and magnetic properties in rare-earth permanent magnets

Gohda

2021

Science and Technology of Advanced Materials

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Development of high-performance permanent magnets relies on both the main-phase compound with superior intrinsic magnetic properties and the microstructure effect for the prevention of magnetization reversal. In this article, the microstructure effect is discussed by focusing on the interface between the main phase and an intergranular phase and on the intergranular phase itself. First, surfaces of main-phase grains are considered, where a general trend in the surface termination and its origin are discussed. Next, microstructure interfaces in SmFe 12 -based magnets are discussed, where magnetic decoupling between SmFe 12 grains is found for the SmCu subphase. Finally, general insights into finite-temperature magnetism are discussed with emphasis on the feedback effect from magnetism-dependent phonons on magnetism, which is followed by explanations on atomic arrangements and magnetism of intergranular phases in Nd-Fe-B magnets. Both amorphous and candidate crystalline structures of Nd-Fe alloys are considered. The addition of Cu and Ga to Nd-Fe alloys is demonstrated to be effective in decreasing the Curie temperature of the intergranular phase.

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“…Trace addition element should fulfill the conditions of good wettability, small solubility to 1–12 grains and low-melting points in order to form the grain boundary phase. However, annealing of the jet-milled powders at temperatures above 600°C resulted in surface decomposition, which occurred by the evaporation of Sm and the remaining Fe and Fe 2 Ti phases at the powder surface, which became more pronounced upon reduction of the particle size [ 64 ] and are detrimental for coercivity. The evaporation of Sm is a more serious problem in sintering process over 1000°C.…”

Section: Recent Progress In Bulk Magnets In Rt 12 -Based Systemsmentioning

confidence: 99%

Recent advances in SmFe₁₂-based permanent magnets

Takahashi

Sepehri-Amin

Ohkubo

2021

Science and Technology of Advanced Materials

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To realize a sustainable society, "green technology" with low (or even zero) CO 2 emissions, is required. A key material in such technology is a permanent magnet because it is utilized for electric-power conversion in several applications including electric vehicles (EVs), hybrid EVs (HEVs), and turbines for wind power generation. To realize highly efficient electric-power conversion, a stronger permanent magnet than Nd-Fe-B is necessary. One potential candidate is a Fe-rich SmFe 12 -based compound with a ThMn 12 structure. In this paper, the phase stability, structure, and intrinsic and extrinsic magnetic properties in both film and bulk forms are reviewed. Based on these results, a possible way to realize a strong SmFe 12 -based permanent magnet in bulk form is discussed.

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Thermal decomposition of ThMn12-type phase and its optimum stabilizing elements in SmFe12-based alloys

Cited by 54 publications

References 31 publications

Structure and Magnetic Properties of Intermetallic Rare-Earth-Transition-Metal Compounds: A Review

Structure and Magnetic Properties of Intermetallic Rare-Earth-Transition-Metal Compounds: A Review

First-principles determination of intergranular atomic arrangements and magnetic properties in rare-earth permanent magnets

Recent advances in SmFe₁₂-based permanent magnets

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Thermal decomposition of ThMn12-type phase and its optimum stabilizing elements in SmFe12-based alloys

Cited by 54 publications

References 31 publications

Structure and Magnetic Properties of Intermetallic Rare-Earth-Transition-Metal Compounds: A Review

Structure and Magnetic Properties of Intermetallic Rare-Earth-Transition-Metal Compounds: A Review

First-principles determination of intergranular atomic arrangements and magnetic properties in rare-earth permanent magnets

Recent advances in SmFe12-based permanent magnets

Contact Info

Product

Resources

About

Recent advances in SmFe₁₂-based permanent magnets