Microstructure of Cu-added Pr-Fe-B magnets: Crystallization of antiferromagnetic Pr6Fe13Cu in the boundary region

Kajitani, Toshiyuki; Nagayama, Katsuhisa; Umeda, T.

doi:10.1016/0304-8853(92)90093-4

Cited by 44 publications

(26 citation statements)

References 7 publications

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“…The results discussed so far, very much favor the spin structure as proposed by Kajitani et al: 8 The Fe moments in the sheets around cϭ0 and 1/2 are strongly ferromagnetically coupled, whereas the coupling between the Fe sheets is antiferromagnetic across the M layer at cϭ1/4. In this structure, the R moments at the 8 f site will couple in the usual ͑ferromagnetically for light-R, ferrimagnetically for heavy-R) way to the moments of the Fe neighbors.…”

Section: ͔͒supporting

confidence: 64%

“…4 A strong debate about the magnetic behavior of the ordered variant has arisen. Claims about ferromagnetism, 5 ferromagnetism with compensation point, 6 and antiferromagnetism 2,7,8 have been made. This controversion has prompted us to prepare the compounds Nd 6 Fe 13 M with M ϭAu, Ag, Cu, and Si single phase as far as possible and to reexamine their magnetic behavior.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
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The magnetic properties of various R 6 Fe 13Ϫx M 1ϩx compounds (RϭLa, Nd, Gd, and Dy͒ crystallizing in the La 6 Co 11 Ga 3 structure have been investigated by magnetic measurements and x-ray diffraction. It is shown that all Nd 6 Fe 13 M compounds with M ϭAu, Ag, Cu, Si, and Ga order antiferromagnetically around 415 K and evidence is provided that the frequently reported, increase of the magnetization at lower temperature is due to impurities. High-field measurements made at 4.2 K on Nd 6Ϫx Dy x Fe 12.7 Ga 1.3 compounds with xϭ0.0, 0.2, 0.5, and 1.0 show that the R-Fe coupling is not yet broken at 35 T. A large hysteresis in the field dependence of the magnetization is present in all compounds including La 6 Fe 11 Al 3 , indicating the role of the Fe-sublattice anisotropy. A theoretical model for the field dependence of the magnetization is constructed, based on local minimization of the free energy. By taking into account the second-and fourth-order magnetocrystalline anisotropy terms, the magnetization behavior of the compounds, including the large hysteresis, can be explained excellently. A structure of ferromagnetically ordered Fe sheets coupling antiferromagnetically to each other is proposed to explain the experimental data. The hydrides of these compounds are all ferromagnetic ͑light R) or ferrimagnetic ͑heavy R) and have an easy magnetization direction along the c axis due to the Fe-sublattice anisotropy. Their ordering temperatures are near 450 K, just slightly above the Néel temperature of the parent compounds, which can be understood from the proposed spin structure.

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Section: ͔͒supporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite

show abstract

“…The absence of a spontaneous magnetization of any significance at 4.2 K suggests that the magnetic structure consists of an antiferromagnetically ordered rare earth sublattice and an antiferromagnetically ordered Fe sublattice [9,11]. For the compounds Pr 6 Fe 13 Ag and Pr 6 Fe 13 Au this was recently confirmed by neutron diffraction [8].…”

Section: Introductionmentioning

confidence: 77%

“…There are two rare earth sites, R 1 (8f) and R 2 (16l) and four Fe sites, Fe 1 (4d), Fe 2 (16k), Fe 3 (16l 1 ) and Fe 4 (16l 2 ). The magnetic properties of the R 6 Fe 13 X compounds were studied by numerous authors [2,[4][5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Magnetic ordering of Pr₆Fe₁₃Si and Nd₆Fe₁₃Au studied by neutron diffraction

Schobinger‐Papamantellos

Buschow

Groot

et al. 1999

J. Phys.: Condens. Matter

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Abstract. The magnetic structure of the compounds Pr 6 Fe 13 Si and Nd 6 Fe 13 Au has been studied by powder neutron diffraction. The magnetic structures are very similar, revealing the same collinear antiferromagnetic ordering of the Fe (four) and the R (two) sublattices associated with the wavevector q = (001) and an I P type magnetic lattice with anticentring translation. The moments of all sublattices located in (xy0) layers and sandwiched between successive Si (Au) layers perpendicular to z at z = −0.25, 0.25, are confined to the same direction within the (xy0) plane. They change their direction collectively when going to the next Au (Si) layers at z = 0.25, 0.75, thus producing antiferromagnetic ordering within all eight sublattices. At 1.5 K, the rare earth moments in Nd 6 Fe 13 Au are equal to 3.4(2) µ B for Nd1 and 2.5(1) µ B for Nd2. In Pr 6 Fe 13 Si the two Pr sites have almost the same moment of 2.8(1) µ B at 1.5 K. The average ordered Fe moment value is lower in Pr 6 Fe 13 Si (1.57 µ B /Fe atom) than in Nd 6 Fe 13 Au (2.3 µ B /Fe atom).

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“…The Nd 6 Fe 14Ϫx M x structure has been found first by Sichevich et al 9 and was later shown by many authors to exist in NdFeB magnets doped with Al,Ga,Cu,Sn. [10][11][12][13][14] Nd 3 Ga 2 has not been found in magnets before, but has been identified by EPMA and electron diffraction and has the I4/mcm symmetry. 15 This result is in contrast with the results of Bernardi et al, 16 who found …”

Section: A Phase Identificationmentioning

confidence: 99%

Two-powder Nd2Fe14B magnets with DyGa-addition

Groot

Buschow

Boer

et al. 1998

Journal of Applied Physics

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Magnetic and structural properties of sintered NdFeB magnets with addition of various amounts of DyGa as a separate powder are studied and compared with single-powder magnets of the same nominal composition. When the magnets are annealed above 640°C, the coercivity decreases strongly as compared to magnets annealed below 640°C. Decomposition of the ␦ phase ͑Nd 6 Fe 14Ϫx Ga x ) accompanies this drop. Measurements of coercivity as a function of temperature show that the decomposition of the ␦ phase does not increase the effective demagnetization factor, but enlarges either the magnetic inhomogeneous region at the grain surface or the exchange coupling between the grains. Line faults, which are present within the Nd 2 Fe 14 B grains when the magnet is annealed below 640°C, do not act as pinning centers. Phase analysis and diffusion profiles of the Dy and Ga concentration within the grains are made using electron probe micro-analysis. This shows that Ga forms Nd 3 Ga 2 and Nd 6 Fe 12.7 Ga 1.3 as intergranular phases. Its concentration within the ⌽ phase is significantly lower than in the ⌽ phase of single-powder magnets. At 1090°C, a diffusion coefficient for Ga of Dϭ2.5Ϯ0.1ϫ10 Ϫ15 m 2 /s is found. Dy is shown only to be present in that part of the Nd 2 Fe 14 B grain which has precipitated from the liquid during sintering. At the boundary of the Dy-free center and the outer part of the grain, an increased Dy concentration is found.

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Microstructure of Cu-added Pr-Fe-B magnets: Crystallization of antiferromagnetic Pr6Fe13Cu in the boundary region

Cited by 44 publications

References 7 publications

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite

Magnetic ordering of Pr₆Fe₁₃Si and Nd₆Fe₁₃Au studied by neutron diffraction

Two-powder Nd2Fe14B magnets with DyGa-addition

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Microstructure of Cu-added Pr-Fe-B magnets: Crystallization of antiferromagnetic Pr6Fe13Cu in the boundary region

Cited by 44 publications

References 7 publications

Magnetic properties ofR6Fe13−xM1+xGroot1, Buschow2, Boer3 1998Phys. Rev. B515200View full textAdd to dashboardCite

Magnetic properties ofR6Fe13−xM1+xGroot1, Buschow2, Boer3 1998Phys. Rev. B515200View full textAdd to dashboardCite

Magnetic ordering of Pr6Fe13Si and Nd6Fe13Au studied by neutron diffraction

Two-powder Nd2Fe14B magnets with DyGa-addition

Contact Info

Product

Resources

About

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite

Magnetic ordering of Pr₆Fe₁₃Si and Nd₆Fe₁₃Au studied by neutron diffraction