Magnetic and crystallographic characteristics of rare-earth ternary carbides derived from R2Fe17 compounds

Zhong, X.P.; Radwański, R. J.; Boer, F.R. de; Jacobs, T.H.; Buschow, K.H.J.

doi:10.1016/0304-8853(90)90141-c

Cited by 264 publications

(40 citation statements)

References 9 publications

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“…Since the Nd concentration of Nd 2 Fe 17 B x grains agrees well with the stoichiometry of the binary Nd 2 Fe 17 , the weak alloy composition-dependence of its lattice parameter c and the distribution of its Curie temperature over a narrow range can be related to a variable concentration of boron atoms. It has been well-documented that interstitial dissolution of metalloid atoms such as hydrogen, carbon and nitrogen can expand the lattice of the binary Nd 2 Fe 17 , leading to an enlargement of the interatomic distance of the Fe sublattice and hence to a significant increase of the Curie temperature [11][12][13][14][15]. Because boron atoms have a much larger atomic radius, they are expected to yield a more significant lattice expansion and thus more pronounced enhancement of the Curie temperature than those atoms.…”

Section: Structure and Stoichiometry Of Nd 2 Fe 17 B Xmentioning

confidence: 97%

Crystallization of Nd2Fe17Bx from stoichiometric melt composition

Gao¹,

Volkmann²,

Yang³

et al. 2007

Journal of Alloys and Compounds

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Section: Structure and Stoichiometry Of Nd 2 Fe 17 B Xmentioning

confidence: 97%

Crystallization of Nd2Fe17Bx from stoichiometric melt composition

Gao¹,

Volkmann²,

Yang³

et al. 2007

Journal of Alloys and Compounds

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“…No direct determination of the CF excitations in Sm 2 Fe 17 and its nitride and carbide by inelastic neutron scattering has been carried out hitherto, so experimental CF parameters for these compounds have only been derived from magnetization measurements. In these experiments 6,7,9,67,80 the anisotropy fields and their temperature dependence have been determined by high field magnetization or singular point detection measurements on aligned powders since single crystals of these materials have not been available. Deriving the CF parameters from these data 7,79,[81][82][83][84] is not free of ambiguity, since a number of parameters ͑CF and exchange parameters͒ have to be determined by fitting of a single curve without a pronounced structure and the R sublattice anisotropy has to be separated from the T sublattice anisotropy.…”

Section: Calculated Crystal-field Parametersmentioning

confidence: 99%

“…The saturation magnetization at room temperature is enhanced considerably. 5,6 Improvement of the intrinsic magnetic properties of Sm 2 Fe 17 can also be achieved with interstitial carbon, 8,9 but in this case the maximum occupancy of the interstitial sites 10 and-partially as a consequence-the enhancement of T C and magnetization as well as the uniaxial anisotropy field are lower than with nitrogen. The rhombohedral Th 2 Zn 17 structure of the parent compound is maintained in the nitride and carbide with a small increase in volume.…”

Section: Introductionmentioning

confidence: 99%

Abinitiocalculation of electronic structure, crystal field, and intrinsic magnetic properties ofSm2Fe1

et al. 1996

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In a comparative study we calculated the spin and orbital moments, spin and charge densities, and 4 f crystal field ͑CF͒ parameters of the rare-earth transition-metal intermetallics Sm 2 Fe 17 , Sm 2 Fe 17 Z 3 (ZϭC,N͒, and Sm 2 Co 17 using a relativistic optimized linear combination of atomic orbitals method. The itinerant valence electron states were treated in the local-spin-density approximation ͑LSDA͒, whereas the localized 4 f states were described as open core states within the self-interaction-corrected LSDA. The calculations yield magnetic moments in good agreement with experiment. While all local moments of Sm 2 Fe 17 increase upon lattice expansion, the moments of atoms neighboring the interstitial sites decrease and those of more distant Fe atoms increase upon insertion of interstitial N or C. In N interstitial atoms all 2p ␣ orbitals are polarized antiparallel to their respective Fe and Sm neighbor atoms in the bond direction, whereas in C all 2p ␣ orbitals are polarized antiparallel to the Fe atoms neighboring the interstitial site. The second-order CF parameters A 2 0 dominating the rare-earth magnetocrystalline anisotropy are found to have the same sign and order of magnitude as those derived from magnetization data. In accordance with experiment the calculated negative A 2 0 is larger for the Co compound than for the Fe parent compound and is strongly increased upon insertion of interstitial N or C. The agreement between theory and experiment is improved by taking into account the CF contribution arising from the asphericity of the exchange-correlation potential of the non-4 f states.

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“…Both T N and Y T are below room temperature and thus too low from an applications perspective. Correspondingly, considerable effort has been spent in attempting to increase Y T /Tc for this series, and such studies have shown that the partial substitution of Fe by nonmagnetic elements such as Si, Al and Ga [3,4], or the absorption of H, N or C into interstitial sites, increases the onset of ferromagnetism in such R 2 Fe 17 compounds significantly [5][6][7]. In contrast, the substitution of Mn -a magnetic species -for Fe produces a complicated behavior, with ferromagnetism being suppressed initially [8].…”

Section: Introductionmentioning

confidence: 98%