Title: Phase stability and coercivity in La₂Fe₁₄B magnet

Abstract

Critical rare-earth free La ₂ Fe ₁₄ B (2:14:1) has the potential to be a gap permanent magnet. However, La ₂ Fe ₁₄ B decomposes into La, α-Fe, and LaFe ₄ B ₄ phases below 1067 K. The phase stability and coercivity have been studied in La ₂ Fe ₁₄ B magnet using first principles DFT (density functional theory) calculation and micromagnetic simulation. For a perfect La ₂ Fe ₁₄ B cube (edge length of 256 nm) without any structural defects and soft magnetic secondary phases, the coercivity (8.5 kOe) is reduced to ∼40% of its magnetocrystalline anisotropy field ( H _A = 20 kOe). Further, the coercivity sharply reduces to 3.2 kOe upon forming a thin layer (2 nm) of α-Fe on the surface of the La ₂ Fe ₁₄ B cube particle. The DFT calculations indicate that a partial replacement of La by other rare-earth (RE) elements can enhance the structural stability of 2:14:1. The gains in cohesive energy are 0.75, 0.10, and 0.33 eV per formula unit in (La _0.5 RE _0.5 ) ₂ Fe ₁₄ B with RE = Ce, Pr, and Nd, respectively. Stabilizing the 2:14:1 structure and mitigating the formation of soft magnetic structural defects or impurity phasesmore » such as α-Fe is necessary to develop La ₂ Fe ₁₄ B based magnet, which can be moderately achieved via partial substitution of La by other rare earth elements such as Ce, Pr, and Nd.« less

Authors:

Liu, X. B.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-2558-0959"

Nlebedim, I. C.  ^[1]

• Search DOE PAGES for author "Nlebedim, I. C."
• Search DOE PAGES for ORCID "0000-0002-0045-4585"

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+ Show Author Affiliations

1. Critical Materials Institute (CMI), Ames, IA (United States)

Publication Date:

Thu Feb 02 00:00:00 EST 2023

Research Org.:

Ames Laboratory (AMES), Ames, IA (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Manufacturing Office

OSTI Identifier:

1923035

Alternate Identifier(s):

OSTI ID: 1923111

Report Number(s):

IS-J-10,993
Journal ID: ISSN 2158-3226; TRN: US2312778

Grant/Contract Number:  

AC02-07CH11358

Resource Type:

Accepted Manuscript

Journal Name:

AIP Advances

Additional Journal Information:

Journal Volume: 13; Journal Issue: 2; Journal ID: ISSN 2158-3226

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE