US-12620511-B2 - Iron nitride magnetic material including coated nanoparticles

Abstract

The disclosure describes techniques for forming nanoparticles including Fe 16 N 2 phase. In some examples, the nanoparticles may be formed by first forming nanoparticles including iron, nitrogen, and at least one of carbon or boron. The carbon or boron may be incorporated into the nanoparticles such that the iron, nitrogen, and at least one of carbon or boron are mixed. Alternatively, the at least one of carbon or boron may be coated on a surface of a nanoparticle including iron and nitrogen. The nanoparticle including iron, nitrogen, and at least one of carbon or boron then may be annealed to form at least one phase domain including at least one of Fe 16 N 2 , Fe 16 (NB) 2 , Fe 16 (NC) 2 , or Fe 16 (NCB) 2 .

Inventors

• Jian-Ping Wang
• Yanfeng Jiang
• Craig A. Bridges
• Michael P. Brady
• Orlando RIOS
• Roberta A. Meisner
• Lawrence F. Allard, JR.
• Edgar Lara-Curzio
• Shihai He

Assignees

• REGENTS OF THE UNIVERSITY OF MINNESOTA
• UT-BATTELLE, LLC
• UNIVERSITY OF TENNESSEE RESEARCH FOUNDATION

Dates

Publication Date

20260505

Application Date

20211028

Claims (9)

1. 1 . A nanoparticle comprising: a core comprising at least one Fe 16 N 2 phase domain; and a coating comprising elemental carbon on the nanoparticle.
2. 2 . The nanoparticle of claim 1 , wherein the coating defines a thickness between about 0.5 nanometers and about 50 nanometers, and wherein the nanoparticle comprises a diameter between about 0.5 nm and about 200 nm.
3. 3 . The nanoparticle of claim 1 , further comprising at least one of a transition metal dopant, a rare earth metal dopant, or an oxide dopant.
4. 4 . The nanoparticle of claim 3 , wherein the transition metal dopant is selected from Co, Mn, Cr, Ni, Ti, La, or combinations thereof.
5. 5 . A bulk magnetic material comprising: a plurality of consolidated nanoparticles, wherein at least one of the plurality of consolidated nanoparticles comprises: a core comprising at least one Fe 16 N 2 phase domain; and a coating comprising elemental carbon formed on the nanoparticle.
6. 6 . The bulk magnetic material of claim 5 , wherein the coating defines a thickness between about 0.5 nanometers and about 50 nanometers, and wherein the nanoparticles comprises diameters between about 0.5 nm and about 200 nm.
7. 7 . The bulk magnetic material of claim 5 , wherein the bulk permanent magnet material has a minimum dimension of at least 0.1 mm.
8. 8 . The nanoparticle of claim 5 , further comprising at least one of a transition metal dopant, a rare earth metal dopant, or an oxide dopant.
9. 9 . The nanoparticle of claim 8 , wherein the transition metal dopant is selected from Co, Mn, Cr, Ni, Ti, La, or combinations thereof.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a divisional of U.S. patent application Ser. No. 15/129,439, filed Sep. 27, 2016, which is a national stage entry under 35 U.S.C. § 371 of International Application No. PCT/US2015/022763, filed Mar. 26, 2015, and claims the benefit of U.S. Provisional Patent Application No. 61/971,730, filed Mar. 28, 2014, all entitled, “IRON NITRIDE MAGNETIC MATERIAL INCLUDING COATED NANOPARTICLES,” the entire contents of which are incorporated by reference herein. GOVERNMENT INTEREST This invention was made with government support under DE-AR0000199 awarded by the U.S. Department of Energy. The government has certain rights in the invention. TECHNICAL FIELD The disclosure relates to iron nitride magnetic materials. BACKGROUND Iron nitride magnets based on the Fe16N2/Fe8N phase are of great interest as a magnetic material for applications ranging from data storage to electrical motors for vehicles, wind turbines, and other power generation equipment. The component base elements (Fe, N) are inexpensive and widely available, in contrast to rare earth elements in rare earth element-based magnets, which are costly and subject to supply availability risks. The Fe16N2 phase, which is the ordered version of Fe8N, has a large magnetic anisotropy constant and saturation magnetization but is exceedingly difficult to manufacture. SUMMARY The disclosure describes techniques for forming nanoparticles including Fe16N2 iron nitride phase. In some examples, the nanoparticles may be formed by first forming nanoparticles including iron, nitrogen, and at least one of carbon or boron. The carbon or boron may be incorporated into the nanoparticles such that the iron, nitrogen, and at least one of carbon or boron are mixed. Alternatively, the at least one of carbon or boron may be coated on a surface of a nanoparticle including iron and nitrogen. The nanoparticle including iron, nitrogen, and at least one of carbon or boron then may be annealed to form at least one phase domain including at least one of Fe16N2, Fe16(NB)2, Fe16(NC)2, or Fe16(NCB)2. In some examples, the nanoparticles may include at least one Fe16N2 phase domain, and additionally may include at least one phase domain of at least one of Fe16(NB)2, Fe16(NC)2, or Fe16(NCB)2. In some examples, the nanoparticles including Fe16N2 iron nitride phase may be formed by forming a nanoparticle including iron and nitrogen, coating the nanoparticle including iron and nitrogen with carbon, boron, or both, and annealing the coated nanoparticle to include at least one Fe16N2 phase domain. In other examples, the nanoparticles including Fe16N2 iron nitride phase may be formed by forming an iron nanoparticle coating the iron nanoparticle with carbon, boron, or both. The coated iron nanoparticle then may be nitridized and annealed to form at least one Fe16N2 phase domain. In some examples, the nanoparticles may include at least one Fe16N2 phase domain, and additionally may include at least one phase domain of at least one of Fe16(NB)2, Fe16(NC)2, or Fe16(NCB)2. In one example, the disclosure describes a method including forming a nanoparticle including iron and nitrogen, coating a surface of the nanoparticle with at least one of carbon or boron to form a coated nanoparticle, and annealing the coated nanoparticle to form at least one Fe16N2 phase domain. In another example, the disclosure describes a nanoparticle formed by any of the techniques described herein. In an additional example, the disclosure describes a system configured to perform any of the techniques described herein. In a further example, the disclosure describes a nanoparticle including a core comprising iron and nitrogen, and a coating comprising at least one of carbon or boron formed on the nanoparticle. In another example, the disclosure describes a system including a source chamber, a deposition chamber, a loadlock chamber, a first sputtering gun at least partially disposed in the source chamber, a second sputtering gun at least partially disposed in the loadlock chamber, and a substrate transfer mechanism operable to move a substrate between the deposition chamber and the loadlock chamber. In a further example, the disclosure describes a method including forming a coating comprising at least one of carbon or boron on a surface of a nanoparticle comprising iron to form a coated iron nanoparticle, and nitriding the coated iron nanoparticle by exposing the coated iron nanoparticle to atomic nitrogen to form a nitride nanoparticle, wherein the nitride nanoparticle comprises at least one Fe16N2 phase domain. In another example, the disclosure describes a method comprising forming a nanoparticle including iron, nitrogen, and between about 0.5 at. % and about 11 at. % of at least one of carbon or boron; and annealing the nanoparticle to form at least one phase domain comprising at least one of Fe16N2, Fe16(NB)2, Fe16(NC)2, or Fe16(NCB)2. The details of one or more examples are s