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Department of Physics and Astronomy

NovoMag

Fe-Co-N ternary compounds

Iron is more preferable than cobalt in permanent magnet applications considering its low price plus that Fe has a larger magnetic moment than Co. Thus by extending our work on the binary Co-N, the ternary Fe-Co-N system has been investigated as rare-earth free magnets [1, 2]. We found substituting a fraction of Co with Fe helps to stabilize the newly proposed structures and at the same time further improve the magnetic properties. 

The crystal structures are directly taken from those for ConN (n = 3–8) obtained in the AGA searches and all possible Fe substitutions are enumerated for each parent structure. It should be noted that the structures of iron nitrides and cobalt nitrides are rather similar due to the similarities between Fe and Co, although the ground-state structure for the same compositions can be different. In fact, we found that all the reported structures for Fe3N, Fe4N and Fe8N in the literature exist in our structure pools of Co–N.

In the following table, the calculated magnetic moment per transition metal (TM) and MAE values are listed. The crystal structures of the listed configurations can be found by clicking the name of each composition.

[1] X Zhao, L Ke, CZ Wang, and KM Ho, Metastable cobalt nitride structures with high magnetic anisotropy for rare-earth free magnets. Physical Chemistry Chemical Physics 18 (46), 31680-31690 (2016).

[2] X Zhao, CZ Wang, Y. X. Yao, and KM Ho, Large magnetic anisotropy predicted for rare-earth free Fe16-xCxN2 alloys. Physical Review B 94 (22), 224424 (2016).

 

(Fe, Co)3N [txt]      

Fe1Co5N2.1

-7.47035

C 1 2 1

M(TM)=0.805412 μB/atom

MAE = -0.29 MJ/m3

Fe1Co5N2.4

-7.44195

A m m 2

M(TM)=1.08878 μB/atom

MAE = 0.73 MJ/m3

Fe1Co5N2.5

-7.44107

C 2/m 2/m 2/m

M(TM)=1.08579 μB/atom

MAE = 1.51 MJ/m3

--

--

--

--

Fe2Co4N2.1

-7.64346

C 2 2 21

M(TM)=0.998925 μB/atom

Triaxial anisotropy

Fe2Co4N2.2

-7.64267

C 1 c 1

M(TM)=0.922825 μB/atom

MAE = -1.13 MJ/m3

Fe2Co4N2.9

-7.6183

A m m 2

M(TM)=1.12756 μB/atom

MAE = 1.68 MJ/m3

--

--

--

--

Fe3Co3N2.1

-7.81671

P 1

M(TM)=1.05669 μB/atom

MAE = -0.89 MJ/m3

Fe3Co3N2.4

-7.80089

A m m 2

M(TM)=1.16098 μB/atom

MAE = 1.54 MJ/m3

Fe3Co3N2.6

-7.79979

A m m 2

M(TM)=1.36449 μB/atom

MAE = 2.50 MJ/m3

--

--

--

--

Fe4Co2N2.1

-7.98879

C 1 2 1

M(TM)=1.29211 μB/atom

MAE = -1.54 MJ/m3

Fe4Co2N2.5

-7.97085

C 2/m 2/c 21/m

M(TM)=1.49513 μB/atom

MAE = 2.22 MJ/m3

Fe4Co2N2.10

-7.96279

A m m 2

M(TM)=1.42332 μB/atom

MAE = 1.64 MJ/m3

--

--

--

--

Fe5Co1N2.1

-8.15858

C 1 2 1

M(TM)=1.43039 μB/atom

Triaxial anisotropy

Fe5Co1N2.4

-8.12622

A m m 2

M(TM)=1.48389 μB/atom

MAE = 1.42 MJ/m3

Fe5Co1N2.5

-8.12154

C 2/m 2/m 2/m

M(TM)=1.54524 μB/atom

MAE = 1.10 MJ/m3

-----------------

------------------

------------------------------

----------------------------------

(Fe. Co)4N [txt]

Fe1Co7N2.1

-7.37181

P 4/m 2/m 2/m

M(TM)=1.3746 μB/atom

MAE = -0.53 MJ/m3

Fe1Co7N2.3

-7.36769

I 4/m 2/m 2/m

M(TM)=1.37355 μB/atom

MAE = 1.06 MJ/m3

--

--

--

--

Fe2Co6N2.1

-7.53209

P 4/m -3 2/m

M(TM)=1.49044 μB/atom

MAE ~ 0 MJ/m3

Fe2Co6N2.3

-7.51883

I 4 m m

M(TM)=1.47866 μB/atom

MAE = 1.54 MJ/m3

--

--

--

--

Fe3Co5N2.1

-7.67426

P 2/m 2/m 2/m

M(TM)=1.55768 μB/atom

MAE ~ 0 MJ/m3

Fe3Co5N2.3

-7.66095

I 4/m 2/m 2/m

M(TM)=1.56437 μB/atom

MAE = 1.02 MJ/m3

Fe3Co5N2.9

-7.65149

I -4 m 2

M(TM)=1.51736 μB/atom

MAE = 1.63 MJ/m3

--

--

--

--

Fe4Co4N2.1

-7.81151

P 4/m 2/m 2/m

M(TM)=1.60031 μB/atom

MAE = -0.46 MJ/m3

Fe4Co4N2.10

-7.79279

I m m 2

M(TM)=1.5812 μB/atom

MAE = 0.92 MJ/m3

--

--

--

--

Fe5Co3N2.1

-7.93252

P 2/m 2/m 2/m

M(TM)=1.64434 μB/atom

MAE = -0.91 MJ/m3

Fe5Co3N2.7

-7.92117

I 4/m 2/m 2/m

M(TM)=1.6677 μB/atom

MAE = 2.40 MJ/m3

--

--

--

--

Fe6Co2N2.1

-8.05045

P m m 2

M(TM)=1.76074 μB/atom

MAE = -0.75 MJ/m3

Fe6Co2N2.4

-8.0493

I 4 m m

M(TM)=1.70771 μB/atom

MAE = 1.06 MJ/m3

--

--

--

--

Fe7Co1N2.1

-8.17125

P 4/m 2/m 2/m

M(TM)=1.86265 μB/atom

MAE = 1.06 MJ/m3

Fe7Co1N2.3

-8.16825

I 4 m m

M(TM)=1.83459 μB/atom

MAE = 0.91 MJ/m3

-----------------

------------------

------------------------------

----------------------------------

(Fe, Co)5N [txt]

Fe2Co8N2.1

-7.43359

A m m 2

M(TM)=1.41332 μB/atom

MAE = 0.78 MJ/m3

Fe2Co8N2.9

-7.42683

A m m 2

M(TM)=1.38048 μB/atom

MAE = 0.78 MJ/m3

Fe2Co8N2.10

-7.42641

I 4/m

M(TM)=1.26867 μB/atom

MAE = -1.86 MJ/m3

--

--

--

--

Fe4Co6N2.1

-7.66212

A m m 2

M(TM)=1.52287 μB/atom

MAE = 1.44 MJ/m3

Fe4Co6N2.3

-7.66162

A m m 2

M(TM)=1.50444 μB/atom

MAE = 1.40 MJ/m3

Fe4Co6N2.5

-7.65985

A m m 2

M(TM)=1.50918 μB/atom

MAE = 1.55 MJ/m3

Fe4Co6N2.6

-7.6597

A m m 2

M(TM)=1.51738 μB/atom

MAE = 1.24 MJ/m3

Fe4Co6N2.7

-7.65928

A m m 2

M(TM)=1.50873 μB/atom

MAE = 1.50 MJ/m3

--

--

--

--

Fe6Co4N2.1

-7.87069

A m m 2

M(TM)=1.57219 μB/atom

MAE = 0.68 MJ/m3

Fe6Co4N2.4

-7.86703

A m m 2

M(TM)=1.5922 μB/atom

MAE = 1.44 MJ/m3

Fe6Co4N2.8

-7.86594

A m m 2

M(TM)=1.57123 μB/atom

MAE = 1.15 MJ/m3

--

--

--

--

Fe8Co2N2.1

-8.06984

A m m 2

M(TM)=1.84668 μB/atom

MAE = 1.50 MJ/m3

Fe8Co2N2.4

-8.06584

P 1 m 1

M(TM)=1.83223 μB/atom

MAE = 1.31 MJ/m3

Fe8Co2N2.7

-8.06509

A m m 2

M(TM)=1.83768 μB/atom

MAE = 1.42 MJ/m3

-----------------

------------------

------------------------------

----------------------------------

(Fe, Co)6N [txt]

Fe2Co10N2.1

-7.37294

P 4 m m

M(TM)=1.46446 μB/atom

MAE = -0.15 MJ/m3

Fe2Co10N2.3

-7.36611

P 4/m 2/m 2/m

M(TM)=1.44994 μB/atom

MAE = 0.33 MJ/m3

Fe2Co10N2.4

-7.36389

P 4 m m

M(TM)=1.44686 μB/atom

MAE = -0.61 MJ/m3

--

--

--

--

Fe4Co8N2.1

-7.57664

P 4/m 2/m 2/m

M(TM)=1.54049 μB/atom

MAE = -0.45 MJ/m3

Fe4Co8N2.2

-7.57227

P m m 2

M(TM)=1.53926 μB/atom

MAE = 0.81 MJ/m3

--

--

--

--

Fe6Co6N2.1

-7.75241

P 2/m 2/m 2/m

M(TM)=1.57732 μB/atom

MAE = 0.58 MJ/m3

Fe6Co6N2.3

-7.75065

P m m 2

M(TM)=1.58234 μB/atom

MAE = 0.76 MJ/m3

Fe6Co6N2.14

-7.74481

P 4/m 2/m 2/m

M(TM)=1.71769 μB/atom

MAE = 1.54 MJ/m3

--

--

--

--

Fe8Co4N2.1

-7.92399

P 4 m m

M(TM)=1.83061 μB/atom

MAE = 1.81 MJ/m3

Fe8Co4N2.2

-7.92234

P 4/m 2/m 2/m

M(TM)=1.88924 μB/atom

MAE = 2.10 MJ/m3

--

--

--

--

Fe10Co2N2.1

-8.09796

P 4/m 2/m 2/m

M(TM)=2.00246 μB/atom

MAE = 0.88 MJ/m3

Fe10Co2N2.2

-8.09264

P 4/m 2/m 2/m

M(TM)=1.98885 μB/atom

MAE = 2.04 MJ/m3

Fe10Co2N2.10

-8.08798

P 4 m m

M(TM)=1.91023 μB/atom

MAE = 1.96 MJ/m3

-----------------

------------------

------------------------------

----------------------------------

(Fe, Co)7N [txt]

Fe2Co12N2.1

-7.32508

A m m 2

M(TM)=1.47764 μB/atom

MAE = -0.30 MJ/m3

Fe2Co12N2.2

-7.32469

C 2/m 2/m 2/m

M(TM)=1.45682 μB/atom

MAE = -1.13 MJ/m3

--

--

--

--

Fe4Co10N2.1

-7.50081

C 2/m 2/m 2/m

M(TM)=1.5763 μB/atom

MAE ~ 0 MJ/m3

Fe4Co10N2.9

-7.49141

A m m 2

M(TM)=1.56204 μB/atom

MAE = 1.06 MJ/m3

--

--

--

--

Fe6Co8N2.1

-7.65329

A m m 2

M(TM)=1.58929 μB/atom

Triaxial anisotropy

Fe6Co8N2.4

-7.65219

A m m 2

M(TM)=1.63734 μB/atom

MAE = 1.46 MJ/m3

Fe6Co8N2.6

-7.65212

A m m 2

M(TM)=1.60556 μB/atom

MAE = 1.55 MJ/m3

Fe6Co8N2.10

-7.65159

A m m 2

M(TM)=1.67101 μB/atom

MAE = 2.11 MJ/m3

--

--

--

--

Fe8Co6N2.1

-7.81238

A m m 2

M(TM)=1.8163 μB/atom

MAE = 1.42 MJ/m3

Fe8Co6N2.3

-7.81121

P 1 m 1

M(TM)=1.78204 μB/atom

MAE = 1.42 MJ/m3

Fe8Co6N2.5

-7.81056

A m m 2

M(TM)=1.80908 μB/atom

MAE = 1.41 MJ/m3

Fe8Co6N2.10

-7.80861

A m m 2

M(TM)=1.80602 μB/atom

MAE = 1.80 MJ/m3

--

--

--

--

Fe10Co4N2.1

-7.9691

A m m 2

M(TM)=1.93671 μB/atom

MAE = -0.71 MJ/m3

Fe10Co4N2.2

-7.96774

P 1 m 1

M(TM)=1.95198 μB/atom

MAE = 1.17 MJ/m3

Fe10Co4N2.6

-7.96555

A m m 2

M(TM)=1.92304 μB/atom

MAE = 1.43 MJ/m3

--

--

--

--

Fe12Co2N2.1

-8.12076

A m m 2

M(TM)=2.04543 μB/atom

MAE ~ 0 MJ/m3

Fe12Co2N2.6

-8.11541

A m m 2

M(TM)=1.986 μB/atom

MAE = 0.92 MJ/m3

Fe12Co2N2.8

-8.11407

A m m 2

M(TM)=1.99391 μB/atom

MAE = 1.23 MJ/m3

-----------------

------------------

------------------------------

----------------------------------

(Fe, Co)8N [txt]

Fe2Co14N2.1

-7.30164

P 4/n 21/m 2/m (origin choice 2)

M(TM)=1.34539 μB/atom

MAE = -0.1 MJ/m3

Fe2Co14N2.2

-7.30037

F -4 3 m

M(TM)=1.34164 μB/atom

MAE ~ 0 MJ/m3

Fe2Co14N2.4

-7.29311

C 2/m 2/m 2/m

M(TM)=1.37694 μB/atom

MAE = -0.4 MJ/m3

--

--

--

--

Fe4Co12N2.1

-7.47033

F 4/m -3 2/m

M(TM)=1.41038 μB/atom

MAE ~ 0 MJ/m3

Fe4Co12N2.4

-7.45078

P 4/m 2/m 2/m

M(TM)=1.49883 μB/atom

MAE = 1.04 MJ/m3

--

--

--

--

Fe6Co10N2.1

-7.5925

I 4 m m

M(TM)=1.39069 μB/atom

MAE ~ 0 MJ/m3

Fe6Co10N2.5

-7.58933

P 2/m 2/m 2/m

M(TM)=1.57258 μB/atom

MAE = 0.82 MJ/m3

--

--

--

--

Fe8Co8N2.1

-7.72733

P 4/m 2/m 2/m

M(TM)=1.86521 μB/atom

MAE = 1.65 MJ/m3

Fe8Co8N2.2

-7.72244

P 4/m 2/m 2/m

M(TM)=1.87292 μB/atom

MAE = 1.12 MJ/m3

Fe8Co8N2.3

-7.72217

P 4/m 2/m 2/m

M(TM)=1.65429 μB/atom

MAE = 1.13 MJ/m3

--

--

--

--

Fe10Co6N2.1

-7.86078

I -4 m 2

M(TM)=1.92279 μB/atom

MAE = -0.29 MJ/m3

Fe10Co6N2.2

-7.86061

P 4 m m

M(TM)=1.95124 μB/atom

MAE = 1.63 MJ/m3

Fe10Co6N2.6

-7.85725

P 4/n 21/m 2/m (origin choice 2)

M(TM)=1.88739 μB/atom

MAE = 2.34 MJ/m3

Fe10Co6N2.10

-7.85549

P 4/m 2/m 2/m

M(TM)=1.88216 μB/atom

MAE = 2.23 MJ/m3

--

--

--

--

Fe12Co4N2.1

-7.99799

I 4/m 2/m 2/m

M(TM)=1.9752 μB/atom

MAE = 1.25 MJ/m3

Fe12Co4N2.2

-7.99733

P 4/m 2/m 2/m

M(TM)=2.05642 μB/atom

MAE ~ 0 MJ/m3

Fe12Co4N2.10

-7.99189

P 2/m 2/m 2/m

M(TM)=1.96714 μB/atom

MAE = 1.93 MJ/m3

Fe12Co4N2.12

-7.99158

P m m 2

M(TM)=1.96887 μB/atom

MAE = 2.15 MJ/m3

Fe12Co4N2.15

-7.99123

I 4/m 2/m 2/m

M(TM)=1.95832 μB/atom

MAE = 3.17 MJ/m3

--

--

--

--

Fe14Co2N2.1

-8.13411

P 4/n 21/m 2/m (origin choice 2)

M(TM)=2.04074 μB/atom

MAE = 1.41 MJ/m3

Fe14Co2N2.3

-8.13233

I -4 m 2

M(TM)=2.07693 μB/atom

MAE = 1.66 MJ/m3

Fe14Co2N2.8

-8.13022

I 4 m m

M(TM)=2.05312 μB/atom

MAE = 1.76 MJ/m3