1. What rare-earth-free magnets are (the short version)

• The aim is the “gap”: the strongest neodymium magnet and the most widely used ferrite magnet are more than tenfold apart in ideal (BH)max, about 516 kJ/m³ and about 45 kJ/m³. A magnet that fills the middle is called a “gap magnet” and is the target for new materials without rare earths, but Coey says the search has met with limited successSourced [Source 1]
• Iron-based materials have enough magnetization but not enough anisotropy: iron nitride and L1₀-FeNi can have magnetization as large as iron, yet the magnetic anisotropy that gives a magnet its resistance to a reverse field (coercivity) is smaller than in rare-earth compounds. There are also walls of stability and processing beyond the material’s propertiesSourced [Sources 1, 2, 5, 7]
• A powder value is not a magnet value: for most candidates, coercivity at the powder, thin-film or small-body stage is only tens to about 200 kA/m, far from sintered neodymium (minimum HcJ of 955 kA/m or more)Sourced [Sources 6, 7, 9, 10, 17]

2. What is to be replaced — the size of the “gap”

Coey writes that the search for new, high-performance rare-earth-free magnet materials to bridge the wide gap between Nd₂Fe₁₄B (ideal (BH)max 515 kJ/m³) and BaFe₁₂O₁₉ (45 kJ/m³) has been less successful. As a price-performance criterion for a “gap magnet” he gives a cost of no more than about one dollar per joule of magnetic energySourced [Source 1]. Prices are not covered here; this article checks the distance in performance.

3. Design thinking — the balance of magnetization and anisotropy

Coey sorts the conditions for a usable magnet material with a hardness parameter κ, the square root of the ratio of anisotropy energy K_u to magnetostatic energy μ₀Ms²: κ = (K_u / μ₀Ms²)^1/2. If κ is above 1, the material makes a magnet of any shape (hard). A κ of 0.1–1 is “semi-hard”, needing help from shape to reduce the demagnetizing field (bars, horseshoes), and a κ of about 0.5 or more makes a magnet possible. But the energy product of a semi-hard magnet stays at only about 10% of the idealSourced [Source 1].

The map reads simply: further right means larger magnetization, higher up means larger anisotropy. Nd₂Fe₁₄B and Sm₂Fe₁₇N₃ sit at the upper right with room to spare inside the κ > 1 region. Ferrite (SrFe₁₂O₁₉) has small magnetization (0.48 T) but enters the κ > 1 region through the balance with its anisotropy. L1₀-FeNi has large magnetization (1.6 T), but its anisotropy ranges from 0.2 to 1.0 MJ/m³ depending on the source, straddling the κ = 0.5 lineSourced [Sources 1, 5, 6, 12].

4. Where each candidate stands — iron nitride, MnAl, tetrataenite, Sm-Fe-N, ferrite, Ce/La substitution

First, a summary table of the candidates. Each number carries the sample form (powder, thin film, consolidated body, natural mineral, theoretical calculation) and its conditions. Values for different forms are not ranked.

All Sourced (source numbers in brackets in each cell). Values for different forms set side by side; not a ranking. Unit conversions: 1 emu/g = 1 A·m²/kg, 1 kOe = 79.577 kA/m.

(1) Iron nitride α″-Fe₁₆N₂ — high magnetization, too little anisotropy

Iron nitride is a metastable phase built from eight bcc iron cells with nitrogen placed at particular sites; the nitrogen makes the lattice tetragonal, and the c-axis becomes the easy axis. Its high saturation magnetization was proposed in 1972 for thin films (as Ogawa describes it)Sourced [Source 7]. Coey surveyed measurements on multiphase bulk samples and electronic-structure calculations and concluded that the average iron moment is in the range 2.3–2.6 μ_B near 0 K, and larger, about 2.9 μ_B, on the 4d sites that have no nitrogen neighbours [Source 8]. Ogawa showed by polarized neutron diffraction that the iron site farthest from nitrogen carries 2.6 ± 0.3 μ_B, larger than the 2.1–2.2 μ_B of bcc iron [Source 7].

To make a magnet, though, difficulties pile up. The powder Ogawa synthesized has a saturation magnetization above iron’s (226 versus 218 A·m²/kg at 300 K) and a magnetocrystalline anisotropy of about 0.96 MJ/m³ [Source 7], but in Coey’s classification iron nitride falls in the semi-hard group (κ below 1) [Source 1]. Hirosawa et al. also say that Fe₁₆N₂ particles face technical difficulties as a base for industrially useful bulk magnets [Source 2]. On consolidation, decomposition at about 200 °C rules out conventional sintering, so the focus is on bonded magnets made by low-temperature forming such as compression molding. Powder set in a magnetic field at a low fill fraction gave a squareness Mr/Ms of 0.80 and a coercivity of 2.5 kOe (about 199 kA/m), but at higher fill fractions c-axis alignment could not be confirmed even when set in fields of 20 kOe or more, says Ogawa [Source 7].

As an example of consolidated bodies, one study nitrided gas-atomized powder and consolidated it by spark plasma sintering (498–598 K, 40–80 MPa); at 548 K and 60 MPa it reports a density of about 80%, a saturation magnetization of about 230 A·m²/kg, a maximum coercivity of about 86.5 kA/m and an Mr/Ms of 0.42. The α″ phase is stable up to about 523 K, and above that decomposition into α-Fe and γ′-Fe₄N proceeds [Source 9]. A route that nitrides a porous alloy made by leaching gave a coercivity of up to 121 kA/m, with a saturation magnetization smaller than iron’s [Source 10].

Ogawa holds that iron nitride will not fully replace rare-earth magnets, and points to partial replacement through nanocomposites with rare-earth magnets, and to the possibility of a new “high-magnetization, low-to-medium-coercivity” magnet that exceeds ferrite and alnico. For an unaligned, resin-bonded sample mixing iron nitride and Sm-Fe-N powders, the magnetization curve was intermediate between the two, suggesting strong magnetic interaction between the particles, resembling exchange coupling [Source 7].

(2) MnAl (τ phase) — cheap elements, and the wall of defects

τ-MnAl is a metastable ferromagnetic phase that appears when Mn is slightly above 50%; Mn and Al form an ordered L1₀ structure. Its magnetization is modest at 0.60 MA/m, its (BH)max is 50 kJ/m³ (a measured value as cited), and its estimated upper bound is about 120 kJ/m³. Because the raw materials are abundant and cheap, it is seen as a material to fill the niche between high-performance rare-earth magnets and general-purpose ferriteSourced [Source 11]. The microstructural problem is antiphase boundaries (APB) and twins. After the τ phase forms, coercivity is relatively low because of APBs, which make domain-wall nucleation easy. A granular structure containing fine twins and APBs can reduce (BH)max to only 5% of its theoretical maximum, the computational paper says, and it should be avoided in manufacturing [Source 11]. Hirosawa et al. say MnAl(C) has a small Js of about 0.7 T and drops out as a candidate for HEV and EV magnets [Source 2].

(3) Tetrataenite L1₀-FeNi — a material meteorites show, and that is hard to make

L1₀-FeNi is an ordered alloy in which iron and nickel atomic layers alternate, and it occurs naturally in iron meteorites that cooled extremely slowly. Goto et al. state a Js of 1.6 T (comparable to Nd-Fe-B), a Curie temperature of 550 °C or higher and a uniaxial anisotropy above 1×10⁶ J/m³ (cited values) [Source 6]. Yet the anisotropy measured in experiments varies by source, 0.2–0.93 MJ/m³ in Woodgate et al.’s table; calculations give 0.23–0.78 MJ/m³, and some analyses suggest it could reach 1.0–1.3 MJ/m³. They attribute the discrepancy to the nanoscale polycrystalline, multivariant microstructure of the experimental samplesSourced [Source 5].

In measurements on tetrataenite from a meteorite (NWA 6259, composition about Fe₅₅Ni₄₄), the microstructure has three mutually orthogonal L1₀ variants that lower remanence; room-temperature coercivity was 95.5 kA/m, the Curie temperature at least 830 K, the anisotropy nearly temperature-independent, and a theoretical energy product possibly exceeding 335 kJ/m³ was suggested preliminarilyNot yet confirmed [Source 4]. The wall to synthesis is that the order-disorder transformation temperature is low, 200–320 °C, and below it atomic diffusion is extremely slow. Goto et al. inserted nitrogen to form FeNiN and then removed it (the NITE method), obtaining a single-phase powder of order parameter S = 0.71 without relying on diffusion, and raised coercivity from 14.5 kA/m (disordered phase) to 142 kA/m [Source 6].

(4) Sm-Fe-N — not rare-earth-free, but without Nd or heavy rare earths

Sm₂Fe₁₇N₃ has intrinsic properties comparable to or better than Nd₂Fe₁₄B — Curie temperature 749 K, μ₀Ms 1.54 T, K₁ 8.6 MJ/m³ — but it decomposes at about 600 °C and cannot be sinteredSourced [Source 1]. Coey says no oriented polymer-bonded magnet so far has exceeded 200 kJ/m³, about half the powder values. Melt-spun Sm-Fe-N powder has an energy product, taken as fully dense, of 164 kJ/m³, which exceeds the expectation for the isotropic case (a quarter of the ideal) thanks to the nanocrystals (about 15 nm on average) [Source 1]. The same paper notes that production is under 1% of Nd-Fe-B and that processing costs are high [Source 1]. IEC 60404-8-1:2023 adds isotropic REFeN bonded magnets [Source 20].

(5) Ferrite — already near its bound; the challenge is sintering

M-type ferrites (BaFe₁₂O₁₉, SrFe₁₂O₁₉) have a Bs of 0.48 T, a Curie temperature more than 150 °C higher than Nd₂Fe₁₄B, are chemically stable, and are the most produced magnet material. The (BH)max of commercial anisotropic magnets is 33.0–41.8 kJ/m³, La-Co substituted products reach up to 44 kJ/m³, and isotropic ones about 10 kJ/m³ (the theoretical value is about 45). Coercivity rises with temperature (in polycrystalline BaM, a maximum of about 380 kA/m near 250 °C) and then fallsSourced [Source 12]. The challenge is keeping coercivity through sintering. Powder coercivity is close to the single-crystal maximum (487–525 kA/m), but sintering at 1,100–1,350 °C makes grains grow, and in consolidated bodies the standard methods mostly give under 300 kA/m [Source 12]. A recent study reports that submicron particles of Ca-La-Co substituted Sr ferrite reached a coercivity of up to 7,880 Oe (about 627 kA/m) without loss of magnetization (71–72 emu/g)Sourced (a laboratory powder value, not a magnet value) [Source 13].

(6) Ce/La substitution — substitution to use “less rare earth”

There are attempts to replace part of the Nd with the more abundant, cheaper La and Ce. Coey says a lattice-matched mixture of La and Ce can be used for the substitution [Source 1], and Pathak et al. report that in Ce-and-Co co-doped alloys the intrinsic coercivity is the highest known for T ≥ 453 KSourced (a research report) [Source 14]. On 20 February 2018 Toyota announced a magnet that replaces part of the Nd with La and Ce, cuts Nd use by up to 50%, uses no Tb or Dy and keeps heat resistance equivalent to earlier neodymium magnets. It names three means: grain refinement to one tenth or less of conventional size, a two-layer grain structure with higher Nd concentration at the grain surface and lower in the core, and a specific ratio of La to CeSourced (company announcement) [Source 15]. The status of practical use was not checked here Not yet confirmed. Hirosawa et al. explain why La and Ce are hard: in T-rich R-T compounds they carry no magnetic moment and contribute little to anisotropy [Source 2]. For the same reason, in rare-earth-lean compounds such as the 1:12 (ThMn₁₂) type, magnetic light rare earths such as Pr, Nd and Sm read as the promising choice [Source 2].

5. The wall of metastable phases — they cannot be sintered

Both neodymium and ferrite magnets become dense by pressing the powder to shape and firing it at high temperature. But many leading rare-earth-free candidates are metastable phases that break down at high temperature. Iron nitride decomposes into α-Fe and γ′-Fe₄N at about 200 °CSourced [Source 7], and Sm-Fe-N decomposes at about 600 °C [Source 1]. L1₀-FeNi has an order-disorder transformation at 200–320 °C, and at temperatures where the ordered phase is stable the atoms barely move, so ordinary heat treatment does not raise the degree of order: it is a material that “cannot be made by waiting” [Source 6]. M-type ferrite, in contrast, is sintered at 1,100–1,350 °C [Source 12].

For iron nitride, ways to consolidate at low temperature are being explored in place of sintering. A body consolidated by spark plasma sintering (548 K) reached only about 80% of theoretical density [Source 9]. As Coey sets out, bonding lowers the share of magnetic powder, and when the powder is not aligned the ideal (BH)max falls further (an ideal 63 kJ/m³ for a random bonded magnet with a fill fraction of 0.7) [Source 1].

6. Powder values versus magnet values — how far coercivity has come

Coey cautions about energy products reported for powders and thin films. For powders, a demagnetizing-field correction is applied and the curve is divided by the fill fraction to bring it to “full density”, so powder values are misleadingly optimistic and magnet values are closer to what an application can expect. A “thin-film permanent magnet”, he adds, is something of an oxymoron: a uniformly magnetized thin film produces almost no field outside, so its energy product is practically zeroSourced [Source 1].

7. How to read company claims

Announcements of practical use by companies are read by keeping targets and plans apart from achievements. What could be confirmed in this article is as follows.

• Toyota (announced 20 February 2018): a magnet that replaces part of the Nd with La and Ce, cutting Nd use by up to 50%, with no Tb or Dy. The announcement says the company will accelerate the development of mass-production technology and aim for early adoption in automobiles and robotics; the status of practical use could not be confirmedNot yet confirmed [Source 15]
• Companies working to commercialize iron nitride magnets: an attempt was made to check Niron Magnetics’ public materials, but the domain assumed to be its official site (niromagnetics.com) could not be resolved from this working environment, so the company’s claims on production timing, performance and plant plans could not be confirmed and are not covered here
• Moves in standardization: IEC 60404-8-1:2023 (4th edition) added hot-deformed REFeB magnets, HDDR REFeB bonded magnets, high-energy ferrites with La and Co substitution, and isotropic REFeN bonded magnets [Source 20]. No standard aimed at iron nitride, MnAl or L1₀-FeNi could be found (Chapter 9)
• Export controls: China’s Ministry of Commerce Announcement No. 62 of 2025 (9 October 2025) made the technology for manufacturing Ce magnets, in addition to Sm-Co and Nd-Fe-B, a controlled “magnet manufacturing” technology, but it is suspended until 10 November 2026 under Announcement No. 70 (checked 10 October 2026)Sourced [Source 27]. The stages are set out in our explainer on permanent magnets and rare earths

Expressions such as “world first” or “groundbreaking” are treated as company or researcher claims; this article gives numbers only with conditions and only as far as the sources say.

8. Limits, and what could not be confirmed

(1) How far the sources were checked

For Kuz’min et al. [Source 3], Lewis et al. [Source 4], Coey (1994) [Source 8], the papers on consolidated iron nitride [Sources 9, 10], Pathak et al. [Source 14] and Cui et al. [Source 16], the publisher’s site could not be reached or the full text is not open, so only the abstract (as listed in a bibliographic database) was checked. The review by Cui et al. (Acta Materialia 158, 118–137) was not read in full, so its contents are not cited.

(2) Iron nitride values

The saturation magnetization of iron nitride is given in A·m²/kg and not converted to tesla, because the density could not be confirmed from a primary source. Company claims about iron nitride magnets (including Niron Magnetics) could not be confirmed. No measured (BH)max for Fe₁₆N₂ as a bulk magnet has been confirmed in the sources used.

(3) MnAl and FeNi values

The anisotropy constant of MnAl and the performance of commercial or prototype MnAl-C magnets could not be confirmed in the sources used. The anisotropy of L1₀-FeNi varies between sources (0.2–1.3 MJ/m³) and is shown here as a range. The estimate of (BH)max by Lewis et al. (above 335 kJ/m³) is preliminary.

(4) Assumptions in the calculations

The “upper limit of Br with iron nitride” in Chapter 3 and the “coercivity needed” in Chapter 6 are rough estimates that assume the rule of thumb for rare-earth magnets that coercivity is 20–30% of the anisotropy field, and a design that uses the (BH)max point. They are not predictions of the performance of iron nitride magnets.

(5) Out of scope

Alnico, cobalt nanowires, exchange-spring magnets, 1:12 thin films, computational screening of new compounds, prices and price forecasts, and the individual effects of additive elements are not covered. For the whole picture of permanent magnets see our explainer on permanent magnets and rare earths, for magnetocaloric materials see our explainer on magnetocaloric materials and magnetic refrigeration, and for magnetic thin-film materials see our explainer on spintronic materials.

9. How to read evaluations and standards

The performance of rare-earth-free candidates divides into intrinsic magnetic properties (Ms, anisotropy, Hk, Curie temperature), first measured on powders or small samples by vibrating-sample magnetometry (VSM), SQUID, torque measurements, switching-field distribution and so on, and the hysteresis of consolidated samples (Br, HcJ, (BH)max). The performance of a magnet (Br, HcJ, (BH)max) is that measured, following a standard, on a sample whose whole volume can be regarded as homogeneous [Sources 19, 23].

Standard numbers, titles and editions in each row are Sourced (checked on IEC, JSA and AFNOR catalogue pages and in the references of an Arnold technical note). Arranging the table is an editorial task of Our calculation. For ASTM standards, the ASTM site was not opened; only numbers and titles confirmed from non-ASTM public sources are given, and no test conditions, procedures or acceptance criteria are described. The texts of the standards are paid and were not checked.

How the positions differ: IEC 60404 is an international standard (TC 68), JIS C 2501 and C 2502 are national standards based on the 2015 editions of IEC 60404-5 and 60404-8-1 (MOD), and ASTM standards are US industry standards. All of them target commercialized magnet families (sintered neodymium, samarium-cobalt, ferrite, bonded magnets); no standard aimed directly at rare-earth-free candidate materials could be found.

Cautions when reading standards

• A standard is a “test method”; it does not guarantee performance. The materials listed in a standard are already commercialized families. Even if a candidate’s number is written as “following the standard”, that does not make the material a grade in the standard
• The same “coercivity” means different things for different sample forms. Powder coercivity, HcJ of a consolidated body and coercivity of a thin film carry different meaning as magnets even with the same number. Check how demagnetizing-field correction and fill fraction were handled
• Values in research papers are neither standard values nor guaranteed values. Read them together with whether they are maximum, typical or minimum values, the temperature, and the number of samples

10. Glossary

11. References (primary sources)

1. Coey J. M. D. “Perspective and Prospects for Rare Earth Permanent Magnets”, Engineering 6, 119–131 (2020), DOI 10.1016/j.eng.2018.11.034 (open access) — doi.org/10.1016/j.eng.2018.11.034
2. Hirosawa S., Nishino M., Miyashita S. (NIMS) “Perspectives for high-performance permanent magnets: applications, coercivity, and new materials”, Adv. Nat. Sci.: Nanosci. Nanotechnol. 8, 013002 (2017), DOI 10.1088/2043-6254/aa597c (open access) — doi.org/10.1088/2043-6254/aa597c
3. Kuz’min M. D. et al. “Towards high-performance permanent magnets without rare earths”, J. Phys.: Condens. Matter 26, 064205 (2014), DOI 10.1088/0953-8984/26/6/064205 (abstract only checked) — doi.org/10.1088/0953-8984/26/6/064205
4. Lewis L. H. et al. “Inspired by nature: investigating tetrataenite for permanent magnet applications”, J. Phys.: Condens. Matter 26, 064213 (2014), DOI 10.1088/0953-8984/26/6/064213 (abstract only checked) — doi.org/10.1088/0953-8984/26/6/064213
5. Woodgate C. D. et al. “Revisiting Néel 60 years on: The magnetic anisotropy of L1₀ FeNi (tetrataenite)”, J. Appl. Phys. 134, 163905 (2023), DOI 10.1063/5.0169752 (full text of the preprint arXiv:2307.15470 checked) — doi.org/10.1063/5.0169752
6. Goto S. et al. “Synthesis of single-phase L1₀-FeNi magnet powder by nitrogen insertion and topotactic extraction”, Sci. Rep. 7, 13216 (2017), DOI 10.1038/s41598-017-13562-2 (open access) — doi.org/10.1038/s41598-017-13562-2
7. Ogawa T. (Tohoku University) “Rare-earth-free α″-Fe₁₆N₂ magnet and its applications”, J. Jpn. Soc. Appl. Electromagnetics and Mechanics 32(3), 524–528 (2024), DOI 10.14243/jsaem.32.524 (open access; in Japanese) — doi.org/10.14243/jsaem.32.524
8. Coey J. M. D. “The magnetization of bulk α″Fe₁₆N₂ (invited)”, J. Appl. Phys. 76, 6632–6636 (1994), DOI 10.1063/1.358156 (abstract only checked) — doi.org/10.1063/1.358156
9. Grigoras M. et al. “Microstructural and Magnetic Evolution of α″-Fe₁₆N₂ Bulk Magnets Consolidated by Spark Plasma Sintering”, Crystals 15(11), 969 (2025), DOI 10.3390/cryst15110969 (abstract only checked) — doi.org/10.3390/cryst15110969
10. Kojima T. et al. “FeNi and Fe₁₆N₂ Magnets Prepared Using Leaching”, Mater. Trans. 60(6), 1066–1071 (2019), DOI 10.2320/matertrans.M2019019 (abstract only checked) — doi.org/10.2320/matertrans.M2019019
11. Arapan S. et al. “Influence of antiphase boundary of the MnAl τ-phase on the energy product”, Phys. Rev. Mater. 3, 064412 (2019) (preprint arXiv:1903.06518 checked) — doi.org/10.1103/PhysRevMaterials.3.064412
12. Granados-Miralles C., Jenuš P. “On the potential of hard ferrite ceramics for permanent magnet technology—a review on sintering strategies”, J. Phys. D: Appl. Phys. 54, 303001 (2021), DOI 10.1088/1361-6463/abfad4 (open access) — doi.org/10.1088/1361-6463/abfad4
13. Lee J. et al. “Anisotropic characteristics and improved magnetic performance of Ca–La–Co-substituted strontium hexaferrite nanomagnets”, Sci. Rep. 10, 15929 (2020), DOI 10.1038/s41598-020-72608-0 (open access) — doi.org/10.1038/s41598-020-72608-0
14. Pathak A. K. et al. “Cerium: An Unlikely Replacement of Dysprosium in High Performance Nd–Fe–B Permanent Magnets”, Adv. Mater. 27, 2663–2667 (2015), DOI 10.1002/adma.201404892 (abstract only checked) — doi.org/10.1002/adma.201404892
15. Toyota Motor Corporation “Toyota Develops New Magnet for Electric Motors Aiming to Reduce Use of Critical Rare-Earth Element by up to 50%” (20 February 2018, news release) — global.toyota/en/newsroom/corporate/21139684.html
16. Cui J. et al. “Current progress and future challenges in rare-earth-free permanent magnets”, Acta Mater. 158, 118–137 (2018), DOI 10.1016/j.actamat.2018.07.049 (abstract only checked) — doi.org/10.1016/j.actamat.2018.07.049
17. Arnold Magnetic Technologies “Neodymium Iron Boron Magnet Catalog” (Rev. 210607) — arnoldmagnetics.com/…/Arnold-Neo-Catalog.pdf
18. Eclipse Magnetics “Ferrite and ceramic magnets datasheet” (distributor datasheet) — eclipsemagnetics.com/…/ferrite_and_ceramic_datasheet.pdf
19. IEC “IEC 60404-5:2015” product page (IEC Webstore) — webstore.iec.ch/en/publication/22142
20. IEC “IEC 60404-8-1:2023” product page (IEC Webstore) — webstore.iec.ch/en/publication/68440
21. IEC “IEC 60404-18:2025” product page (IEC Webstore) — webstore.iec.ch/en/publication/76495
22. Japanese Standards Association (JSA) JIS C 2501:2019 “Methods of test for permanent magnet”, viewing preview (in Japanese) — webdesk.jsa.or.jp/preview/pre_jis_c_02501_000_000_2019_j_ed10_ch.pdf
23. Japanese Standards Association (JSA) JIS C 2500:2022 “Methods of measurement of the magnetic properties of permanent magnet (magnetically hard) materials in an open magnetic circuit using a superconducting magnet”, viewing preview (in Japanese) — webdesk.jsa.or.jp/preview/pre_jis_c_02500_000_000_2022_j_ed10_ch.pdf
24. Japanese Standards Association (JSA) JIS C 2502:2019 “Materials for permanent magnet”, viewing preview (in Japanese) — webdesk.jsa.or.jp/preview/pre_jis_c_02502_000_000_2019_j_ed10_ch.pdf
25. Arnold Magnetic Technologies “What is the Magnetic Hysteresis Loop” (TECHNote TN 1501 rev.2015a; its reference list gives the number and title of ASTM A977M-07, reapproved 2013) — arnoldmagnetics.com/…/Tech-Notes_Hysteresis-Loop.pdf
26. AFNOR “ASTM A1054-16” catalogue page (AFNOR Editions; not an ASTM site) — boutique.afnor.org/…/am95890/275610
27. China, Ministry of Commerce Announcement No. 62 of 2025, decision on export controls on rare-earth technologies, 9 October 2025 (in Chinese) — mofcom.gov.cn/…/art_04a2df12…

12. Claim-to-source audit

Last updated 10 October 2026. Sources are limited to primary material (peer-reviewed papers, a review article from Tohoku University, manufacturers’ stated values, a Toyota announcement, an announcement of China’s Ministry of Commerce, and standards-body catalogue pages). The texts of standards are paid and were not checked. The ASTM International site was not opened, because that body states that AI use of the site is not permitted. For some papers (Kuz’min et al., Lewis et al., Coey 1994, the papers on consolidated iron nitride, Pathak et al. and Cui et al.) only the abstract was checked. Because the article includes values for powders, thin films, small consolidated bodies and natural minerals, and theoretical calculations, please do not read them as magnet performance or as values for production products. Structural readings and materials-design interpretations are marked as Commentary and kept separate from sourced fact. Company claims on iron-nitride magnets (including Niron Magnetics), the measured (BH)max of bulk Fe₁₆N₂ magnets, the anisotropy constant of MnAl and the status of practical use of Toyota’s magnet could not be confirmed and are not stated here. All figures are explanatory concept graphics. Figs. 2 to 4 and 6 are vector drawings; Figs. 1 and 5 are AI-generated images, and none of them shows a real micrograph or physical product.