Magnetic order and defect structure of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Fe</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Al</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mi>−</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>alloys around<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML

Bogner, Johannes R.; Steiner, Walter; Reissner, M.; Mohn, P.; Blaha, Peter; Schwarz, K.; Krachler, Regina; Ipser, Herbert; Sepioł, B.

doi:10.1103/physrevb.58.14922

Cited by 106 publications

(103 citation statements)

References 44 publications

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“…which matches well with the theoretical calculations available in the literature [10,14,15,16,17]. The VB spectra of this system are mainly dominated by Fe 3d states which has major peak at around -1 eV.…”

Section: Resultssupporting

confidence: 78%

“…F e 1−x Al x for x < 0.5 shows other ordered magnetic phases like D03 and B32 [6,7]. The structural characteristics of these alloys have been related to the magnetic properties and different phases like ferromagnetic (FM), paramagnetic (PM), spin-glass (SG) and re-entrant spin glass are reported [6,7,8,9,10]. X-ray photoemission (XPS) valence band of FeAl multilayer sample showed appreciable changes in the Fe 3d and the Al 3s density of states as a function of annealing which are attributed to the strong sp − d hybridization at the Fermi level (E F ) [11].…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure of FeAl alloy studied by resonant photoemission spectroscopy and Ab initio calculations

Mondal

Banik

Kamal

et al. 2016

Journal of Alloys and Compounds

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Abstract. Resonant photoemission spectroscopy has been used to investigate the character of Fe 3d states in FeAl alloy. Fe 3d states have two different character, first is of itinerant nature located very close to the Fermi level, and second, is of less itinerant (relatively localized character), located beyond ∼2 eV below the Fermi level. These distinct states are clearly distinguishable in the resonant photoemission data. Comparison between the results obtained from experiments and first principle based electronic structure calculation show that the origin of the itinerant character of the Fe 3d states is due to the ordered B2 structure, whereas the relatively less itinerant (localized) Fe 3d states are from the disorders present in the sample. The exchange splitting of the Fe 3s core level peak confirms the presence of local moment in this system. It is found that the itinerant electrons arise due to the hybridization between Fe 3d and Al 3s − 3p states. Presence of hybridization is observed as a shift in the Al 2p core-level spectra as well as in the X-ray near edge absorption spectra towards lower binding energy. Our photoemission results are thus explained by the co-existence of ordered and disordered phases in the system.

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Section: Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Electronic structure of FeAl alloy studied by resonant photoemission spectroscopy and Ab initio calculations

Mondal

Banik

Kamal

et al. 2016

Journal of Alloys and Compounds

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“…consistent with the experimental results that give a lattice constant of 5.409 a.u., so that the computed values for the equilibrium lattice constant are underestimated by about 1 %. In addition the spin polarized calculation gives a magnetic moment of 0.63 µ B which is in good agreement with the results obtained in references (13) and (14).…”

Section: Ordered Structuressupporting

confidence: 81%

“…Bogner et al (14) recently showed that it is due to the high density of defects present in this equiatomic alloy. Anyway, we are mainly interested in showing the general trends of the ordered alloys and the effect of the disorder on them, so we will not take this effect into account.…”

Section: Ordered Structuresmentioning

confidence: 99%

Propiedades electrónicas y magnéticas de las aleaciones Fe-Al

Apiñaniz¹,

Plazaola²

2000

Bol. Soc. Esp. Ceram. Vidr.

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This work presents ab-initio self-consistent calculations performed with the TB-LMTO code to study the different phases of the Fe-Al phase diagram, corresponding to the ordered structures B2, DO3 and B32 and for Fe 50 Al 50 and Fe 3 Al compositions. Both, unpolarized and spin-polarized calculations have been performed to deduce the energetic difference between the paramagnetic and ferromagnetic state of the corresponding structure. Calculations for the disordered structures have also been performed for the previously mentioned compositions. These results show that by disordering the alloy magnetism is enhanced and that the equilibrium lattice parameter increases. Keywords: Fe-Al alloys, TB-LMTO code, magnetic transformations, order-disorder. Propiedades electrónicas y magnéticas de las aleaciones Fe-AlEn este trabajo se presentan cálculos autoconsistentes ab-initio realizados con el método TB-LMTO (Tight Binding Linear Muffin Tin Orbital) con el fin de estudiar las diferentes estructuras que se presentan en el diagrama de fases de las aleaciones Fe-Al. Se han estudiado las estructuras ordenadas B2, DO3 y B32 para las siguientes concentraciones: Fe50Al50 y Fe3Al. Asimismo, se han realizado cálculos teniendo y sin tener en cuenta la polarización de spin con el fin de poder deducir la diferencia energética entre los estados ferromágneticos y paramágneticos de la misma estructura. Por otra parte se han realizado estos mismos cálculos para estructuras desordenadas y las mismas concentraciones. Los resultados muestran que mediante el desorden aumenta el magnetismo de estas aleaciones y crece el parámetro de red. Palabras clave: Aleaciones Fe-Al, código TB-LMTO, transformaciones magnéticas, orden-desorden.room temperature), B32 long range order was observed by Becker and Schweike in neutron scattering experiments (4). Calculations of model alloys show that the B32 phase has a tendency to exist at even larger deviations from stoichiometry than the B2 phase.It has been shown that these alloys are of the ferromagnetic disordered type (BCC, A2) for Al concentrations up to 23 at % Al independent of heat treatment (5). In alloys with Al content ranging from 0 to 30 at % the iron atoms carry their normal magnetic moment of 2.2 µ B when they have at least five or more iron atoms as nearest neighbours (6). The 30 at % Al composition is critical for these systems were the average magnetic moment per Fe atom decreases rapidly from 2.0 to 0.7 µ B ; coupled with this there is a large fall in the lattice parameter associated with a fall in the atomic radii as the disorder to order transition occurs (20 to 30 at % Al).By disordering the alloy paramagnetic-ferromagnetic transitions can be induced and these transitions could be related to the changes in volume and not only to nearest neighbour effects as is commonly assumed. As an example we can mention that x-ray diffraction of ball milled alloy of composition Fe 60 Al 40 shows an increase of the lattice parameter with milling time (7). This lattice parameter increase has been assumed...

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“…Although magnetic susceptibility, Mössbauer, and nuclear magnetic resonance measurements indicate that perfectly ordered, stoichiometric FeAl is nonmagnetic in nature, 31,32 an FM ground state is found by DFT (both LDA and GGA) with a local magnetic moment of ∼0.7 µ B for Fe. 33 This FM state is only slightly lower in energy (7 meV/ atom) than the nonmagnetic (NM) state. Since the FM and NM states are almost degenerate and there are still controversies regarding the true ground state of FeAl, 34,35 we choose the NM state to model bulk FeAl and surfaces for simplicity.…”

Section: Calculational Detailsmentioning

confidence: 99%

Effects of Alloying on the Chemistry of CO and H₂S on Fe Surfaces

Jiang

Carter

2005

J. Phys. Chem. B

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Deleterious gases such as CO and H 2 S can cause degradation of steel by reacting with the metal surface. Here we consider whether alloying the steel surface might be able to inhibit these damaging surface reactions by raising the barriers to molecular dissociation. We employ first-principles density functional theory techniques to investigate the elementary reaction pathways and barriers for CO and H 2 S on FeAl and Fe 3 Si surfaces and compare them with pure Fe surfaces (as a model for steel). We find that H 2 S dissociates on iron surfaces much more easily than CO does. Although FeAl surfaces raise the barriers for H 2 S dissociation, they significantly lower the barriers for CO dissociation. On the other hand, Fe 3 Si surfaces raise the barriers for CO dissociation, but they are as vulnerable as Fe surfaces to H 2 S dissociation. Our findings suggest that alloying iron with Al or Si is unlikely to simultaneously increase its resistance to the initial stages of chemical degradation by CO and H 2 S.

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Magnetic order and defect structure ofFexAl1−xalloys around
Johannes R. Bogner
¹
,
Walter Steiner
²
,
M. Reissner
³

et al.

Cited by 106 publications

References 44 publications

Electronic structure of FeAl alloy studied by resonant photoemission spectroscopy and Ab initio calculations

Electronic structure of FeAl alloy studied by resonant photoemission spectroscopy and Ab initio calculations

Propiedades electrónicas y magnéticas de las aleaciones Fe-Al

Effects of Alloying on the Chemistry of CO and H₂S on Fe Surfaces

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Magnetic order and defect structure ofFexAl1−xalloys aroundJohannes R. Bogner1, Walter Steiner2, M. Reissner3 et al.

Cited by 106 publications

References 44 publications

Electronic structure of FeAl alloy studied by resonant photoemission spectroscopy and Ab initio calculations

Electronic structure of FeAl alloy studied by resonant photoemission spectroscopy and Ab initio calculations

Propiedades electrónicas y magnéticas de las aleaciones Fe-Al

Effects of Alloying on the Chemistry of CO and H2S on Fe Surfaces

Contact Info

Product

Resources

About

Magnetic order and defect structure ofFexAl1−xalloys around
Johannes R. Bogner
¹
,
Walter Steiner
²
,
M. Reissner
³

et al.

Effects of Alloying on the Chemistry of CO and H₂S on Fe Surfaces