Valence-electron contributions to the electric-field gradient in hcp metals and at Gd nuclei in intermetallic compounds with the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">ThCr</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Si</mml:mi></mml:mrow

Coehoorn, R.; Buschow, K.H.J.; Dirken, M.W.; Thiel, R.C.

doi:10.1103/physrevb.42.4645

Cited by 147 publications

(29 citation statements)

References 17 publications

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“…The second-order crys- tal field term is related to the electrical field gradient tensor element Vzz by the empirical relation: A2o = -toVzz, where to is an empirical factor which varies from 30-35 Kao 2 mV-1 [12]. Although there is no thorough physical basis for this relation, there are several groups of compounds for which this empirical relation holds [13].…”

Section: Introductionmentioning

confidence: 99%

155Gd Mössbauer effect studies and magnetic properties of GdFe12−xMox(Ny) compounds

Middleton

Mulder

Thiel

et al. 1995

Journal of Magnetism and Magnetic Materials

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Structural and magnetic properties of the GdFe12_~MOx compounds having the ThMn12 type of structure were studied. Rare-earth nitrides of the composition GdFe 12-x MOx N y were prepared by the reaction of GdFe12_x MOx with nitrogen gas at 475°C. The crystal structure and lattice constants have been determined for all compounds. The lattice expansion of the nitrogenated compounds is mainly along the a-axis, the Curie temperatures are increased by about 110 K. We investigated the effect of interstitial nitrogen on the magnetic properties and the 155Gd M/Sssbauer spectrum of GdFe12_xMO x. Values of the electric field gradient V~z derived from the quadrupole splitting of the spectra were strongly negative, with Vzz = -21.3 X 1021 V m -2 and Vzz = -19.9 × 1021 V m -2 for x = 1.5 and 3.0, respectively. Nitrogenation is shown to lead to a sign reversal of the 4f as well as of the 3d sublattice anisotropies.

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Section: Introductionmentioning

confidence: 99%

155Gd Mössbauer effect studies and magnetic properties of GdFe12−xMox(Ny) compounds

Middleton

Mulder

Thiel

et al. 1995

Journal of Magnetism and Magnetic Materials

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“…From band structure calculations it follows that a charge of the Wigner-Seitz cell of Gd ion is approximately Oe when performed for ThCr 2 Si2-type compounds [2]. For GdCo5 [4] the Gd charge changes from -0.32e to +0.21e depending on the Wigner-Seitz radii.…”

Section: Pauling's Chemical Bond Modelmentioning

confidence: 99%

“…The unit cell of the ThMn12 structure. parameters in various rare earth-transition metal compounds [1,2,4], the nearest neighborhood in the vicinity of R atoms has the most important role in describing electric field gradient which "sees" the rare earth ion.…”

Section: Pauling's Chemical Bond Modelmentioning

confidence: 99%

“…Recent band structure calculations [1][2][3][4] showed that in the rare earth-transition metal intermetallic compounds the asphericity of the valence electron charge density of the rare earth atoms itself forms the dominant contribution to the lowest order crystal field parameter A 2 0 ; the lattice contribution has also its influence. The above results are in contradiction with frequently used point charge calculations ( PCC), where the charges outside the central atom produce dominant electric field gradient at the rare earth site.…”

Section: Introductionmentioning

confidence: 99%

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Single-Ion Rare Earth Anisotropy in ThMn₁₂-Type Compounds

Stefański

1994

Acta Phys. Pol. A

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The single-ion rare earth anisotropy was investigated in ThMni2-type compounds. For this purpose the crystal electric field parameter values were studied. In these compounds, described by formula RFe 12_xTx , R = rare earth, T = Ti, V, Cr, Mo, W and Si, the T atoms have strong crystallographic site preference changing the local crystal electric field potential which "sees" the rare earth ion. The crystal electric field potentials A20 were calculated considering this site preference. The summations were performed taking into account the nearest neighborhood of the rare earth ion according to the recent results of band structure calculations. The charges of the surrounding Fe and T atoms were established applying the chemical bond model proposed by Pauling. The absolute value of A3 decreases when the content of vanadium increases in 8(i) position, which is in agreement with experimental data. Localization of Si atoms in 8(j) and 8(f) causes a decrease in A 20. The 1 55 GdMössbauer spectroscopy data confirm this fact. Miedema's "macroscopic" atom model of cohesion in alloys was applied for interpretation of the role of T atoms in the isomer shift and volume effects.

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“…The structure of ρ 20 (2) allows one to analyze separately contributions to ϑ zz of states located at different regions of energy scale and for different sets of (l, l ) orbital quantum numbers. Within approximations used in the calculations, the contribution to EFG of deep true core states is omitted, but as argued in [9,10], their contribution to ϑ zz is negligible. The investigations reported in [9,11] for the series of hcp metals and some iron compounds have proven that the procedure of calculations based on formula (1) give the results in very good agreement with experimental data.…”

Section: MM Lllmentioning

confidence: 99%

Ab Initio Study of the⁵⁷Fe Electric Field Gradient in (FeAl)_1-xT_x(T = 3d Element) Dilute Alloys with B2-Type Structure

et al. 2008

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We present an ab initio study of the electric field gradient at Fe nuclei in the series of (FeAl) 1−x T x dilute alloys with B2-type crystal structure. The ternary additions T, of concentration x ≈ 0.06, from the group of 3d-type transition metals (Ti, V, Cr, Mn, Co, Ni, Cu) are considered. Lattice, local valence electron (3d, 4p) and weakly bound 3p core electron contributions to electric field gradient are separated out and discussed in the context of the T-atom site preference and changes of the electronic structure upon alloying. Contrary to earlier reports, we found that for most Fe nuclei the dominant contribution comes from the d-type valence electrons cancelled partially by the 3p and 4p electric field gradients which are both of opposite sign to that of the 3d one. The shielding effect of 3p semicore electrons is found and related to the electric field gradient contributed by the local valence electrons.

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Valence-electron contributions to the electric-field gradient in hcp metals and at Gd nuclei in intermetallic compounds with theThCr2Si

Cited by 147 publications

References 17 publications

155Gd Mössbauer effect studies and magnetic properties of GdFe12−xMox(Ny) compounds

155Gd Mössbauer effect studies and magnetic properties of GdFe12−xMox(Ny) compounds

Single-Ion Rare Earth Anisotropy in ThMn₁₂-Type Compounds

Ab Initio Study of the⁵⁷Fe Electric Field Gradient in (FeAl)_1-xT_x(T = 3d Element) Dilute Alloys with B2-Type Structure

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Valence-electron contributions to the electric-field gradient in hcp metals and at Gd nuclei in intermetallic compounds with theThCr2Si

Cited by 147 publications

References 17 publications

155Gd Mössbauer effect studies and magnetic properties of GdFe12−xMox(Ny) compounds

155Gd Mössbauer effect studies and magnetic properties of GdFe12−xMox(Ny) compounds

Single-Ion Rare Earth Anisotropy in ThMn12-Type Compounds

Ab Initio Study of the57Fe Electric Field Gradient in (FeAl)1-xTx(T = 3d Element) Dilute Alloys with B2-Type Structure

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Product

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Single-Ion Rare Earth Anisotropy in ThMn₁₂-Type Compounds

Ab Initio Study of the⁵⁷Fe Electric Field Gradient in (FeAl)_1-xT_x(T = 3d Element) Dilute Alloys with B2-Type Structure