Compositional variation of the phonon dispersion curves of bcc Fe-Ga alloys

Zarestky, J.; Garlea, V. Ovidiu; Lograsso, Thomas A.; Schlagel, Deborah L.; Stassis, C.

doi:10.1103/physrevb.72.180408

Cited by 21 publications

(15 citation statements)

References 36 publications

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“…In defining these functions, we assume that the phonons do not change dramatically when Ga is substituted for Fe. This is true for most of the phonon branches with the exception of the transverse ͓110͔ phonons that are known to soften with the addition of Ga. 17 Small static displacements of atoms from their nominal positions in an alloy are caused by size differences of the two…”

Section: Discussionmentioning

confidence: 99%

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Relation between Ga ordering and magnetostriction of Fe-Ga alloys studied by x-ray diffuse scattering

Huang

Chang

et al. 2010

Phys. Rev. B

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Transmission synchrotron diffraction was employed to characterize the Ga ordering in magnetostrictive Fe 100−x Ga x alloys with Ga concentrations from 0 to 20.3 at. %. The experiments focused on the development of atomic short-range ordering (SRO) by analysis of the diffuse scattering appearing at superlattice positions of the D0 3 ordered alloy structure. No SRO was found for Ga concentrations less than 4 at. %. Between 13 and 20.3 at. %, D0 3 -type SRO clusters are observed whose size increases with Ga concentration for both slowcooled and quenched samples. Thermal quenching of the samples suppresses the cluster sizes when compared to slow-cooled samples of the same concentration. For quenched samples with large Ga concentration, Ga pairing is evidenced by growing B2-type correlations. At low concentrations, the presence of SRO appears to have little (if any) effect on the enhanced magnetostriction. However, the dramatic suppression of magnetostriction near ∼20 at. % Ga can be linked rapid growth of SRO just before the onset of long-range chemical order. Transmission synchrotron diffraction was employed to characterize the Ga ordering in magnetostrictive Fe 100−x Ga x alloys with Ga concentrations from 0 to 20.3 at. %. The experiments focused on the development of atomic short-range ordering ͑SRO͒ by analysis of the diffuse scattering appearing at superlattice positions of the D0 3 ordered alloy structure. No SRO was found for Ga concentrations less than 4 at. %. Between 13 and 20.3 at. %, D0 3 -type SRO clusters are observed whose size increases with Ga concentration for both slowcooled and quenched samples. Thermal quenching of the samples suppresses the cluster sizes when compared to slow-cooled samples of the same concentration. For quenched samples with large Ga concentration, Ga pairing is evidenced by growing B2-type correlations. At low concentrations, the presence of SRO appears to have little ͑if any͒ effect on the enhanced magnetostriction. However, the dramatic suppression of magnetostriction near ϳ20 at. % Ga can be linked rapid growth of SRO just before the onset of long-range chemical order.

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Section: Discussionmentioning

confidence: 99%

“…17 Figure 5 shows an example of the calculated TDS compared to the normalized data ͑measured with background removed͒ along ͓1LL͔ direction in reciprocal space. The calculated results are useful for identifying features of the diffuse scattering that arise from thermal vibrations, as opposed to Ga ordering.…”

Section: Discussionmentioning

confidence: 99%

Relation between Ga ordering and magnetostriction of Fe-Ga alloys studied by x-ray diffuse scattering

Huang

Chang

et al. 2010

Phys. Rev. B

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“…% Ga crystals used in the previous lattice dynamical study. 7 Sample preparation details can be found there. Those measurements determined that the 16.0 at.…”

Section: Methodsmentioning

confidence: 99%

“…Further insight to the extraordinary magnetoelastic behavior in this system was provided by inelastic neutron scattering measurements 7 on the Fe-Ga system, performed on a series of compositions ͑Fe 1−x Ga x , x = 0.108, 0.133, 0.160, 0.225, and 0.288͒ that showed all branches soften with increased Ga concentration. Most notably, however, was that the T 2 ͓110͔ branch ͑polarization in the ͓110͔ direction͒ softened dramatically by 50% over the composition range studied.…”

Section: Introductionmentioning

confidence: 99%

Spin-wave dispersion in magnetostrictive Fe-Ga alloys: Inelastic neutron scattering measurements

et al. 2007

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Fe-Ga alloys of appropriate Ga concentration and heat treatment show a very large enhancement in the tetragonal magnetostriction over that of pure α-Fe [λ 100 (Fe-Ga)∼15λ 100 (Fe)]. In order to gain further understanding of the extraordinary magnetoelastic characteristics of this system, the spin dynamics of two of these alloys, Fe 1−x Ga x (x=0.160 and 0.225), were studied using inelastic neutron scattering techniques. The correlation of the spin-wave dispersion curve with the lattice constant and atomic radii of solute is examined for this and other Fe alloys. Disciplines Condensed Matter Physics | Metallurgy CommentsThis article is from Physical Review B 75 (2007) Fe-Ga alloys of appropriate Ga concentration and heat treatment show a very large enhancement in the tetragonal magnetostriction over that of pure ␣-Fe ͓ 100 ͑Fe-Ga͒ϳ15 100 ͑Fe͔͒. In order to gain further understanding of the extraordinary magnetoelastic characteristics of this system, the spin dynamics of two of these alloys, Fe 1−x Ga x ͑x = 0.160 and 0.225͒, were studied using inelastic neutron scattering techniques. The correlation of the spin-wave dispersion curve with the lattice constant and atomic radii of solute is examined for this and other Fe alloys.

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“…It is also interesting to note that Fe 1−x Ga x alloys display dramatic elastic softening within the same concentration range as the appearance of giant magnetostriction. 19 There is evidence that this enhancement is not an intrinsic property of a homogeneous ferromagnetic phase; rather the value of λ 100 is known to depend on the heat treatment of the sample, as it varies with the cooling rate after annealing and with the annealing temperature. [20][21][22][23][24][25] A structurally heterogeneous model 25 has been proposed to explain the enhanced magnetostriction and elastic softening for Fe 1−x Ga x alloys.…”

Section: Introductionmentioning

confidence: 99%

X-ray diffraction study of the pressure-induced bcc-to-hcp phase transition in the highly magnetostrictive Fe0.81Ga0.19alloy

Ahart

Devreugd

et al. 2013

Phys. Rev. B

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High-pressure x-ray diffraction measurements were performed at room temperature on single crystals of the highly magnetostrictive alloy Fe 0.81 Ga 0.19 (galfenol). This alloy has a bcc crystal structure at ambient pressure but undergoes a bcc-to-hcp phase transition at 24 GPa on compression. A large hysteresis loop is observed in which the reversed transition occurs at 13 GPa on decompression. The midpoint of this transition is 18.5 GPa. The measured bulk modulus of this material is 182 ( ± 17) GPa, which is comparable to that of pure iron. As with iron, the hcp structure of the alloy can be derived from a compression of the bcc lattice along [001] that is accompanied by shearing along [110]. Our results indicate that the addition of Ga shifts the bcc-to-hcp transition from 13 GPa in pure iron to 18.5 GPa, and we speculate that this is due to the larger atomic radius of Ga. A uniaxial loading of 3 GPa completely suppresses the diffuse scattering in Fe 0.81 Ga 0.19. We ascertain that the magnetostrictive properties of the alloy are reduced under pressure.

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Compositional variation of the phonon dispersion curves of bcc Fe-Ga alloys

Cited by 21 publications

References 36 publications

Relation between Ga ordering and magnetostriction of Fe-Ga alloys studied by x-ray diffuse scattering

Relation between Ga ordering and magnetostriction of Fe-Ga alloys studied by x-ray diffuse scattering

Spin-wave dispersion in magnetostrictive Fe-Ga alloys: Inelastic neutron scattering measurements

X-ray diffraction study of the pressure-induced bcc-to-hcp phase transition in the highly magnetostrictive Fe0.81Ga0.19alloy

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