Synthesis, crystal structure and Mössbauer effect studies of Dy(Mn0.4Fe0.6−xAlx)2 intermetallics (original) (raw)
2004, Journal of Alloys and Compounds
It was previously found, that the magnetic hyperfine fields observed at 57 Fe nuclei (4.2 K) in the Dy(Mn 1−x Fe x ) 2 and Dy(Fe 1−x Co x ) 2 intermetallics form a Slater-Pauling curve. Both 3d sub-bands in the Dy(Mn 0.4 Fe 0.6 ) 2 compound are filled up only partially with 3d electrons. The consequence of Fe/Al substitution, in the Dy(Mn 0.4 Fe 0.6 ) 2 compound, was studied in the present paper. For this purpose the synthesis and X-ray analysis (300 K) of the series Dy(Mn 0.4 Fe 0.6−x Al x ) 2 were performed. The cubic, MgCu 2 -type, Fd3m crystal structure was observed across the series. 57 Fe Mössbauer effect measurements for the series were realized at 4.2 K. The obtained crystallographic data and the hyperfine interaction parameters are presented. The magnetic hyperfine fields form a separate branch of the Slater-Pauling curve. The data are qualitatively related to the Stoner model.
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Mössbauer effect studies of Dy(Mn0.4−xAlxFe0.6)2 compounds
Journal of Alloys and Compounds, 2004
It was previously found that the magnetic hyperfine fields observed at 57 Fe nuclei (4.2 K) in the Dy(Mn 1−x Fe x ) 2 and Dy(Fe 1−x Co x ) 2 intermetallics form a Slater-Pauling curve. Both 3d subbands in the Dy(Mn 0.4 Fe 0.6 ) 2 compound are filled up only partially with 3d electrons. The consequence of Mn/Al substitution, in the Dy(Mn 0.4 Fe 0.6 ) 2 compound was studied in the present paper. For this purpose the synthesis and X-ray analysis (300 K) of the series Dy(Mn 0.4−x Al x Fe 0.6 ) 2 were performed. The cubic, MgCu 2 -type Fd3m crystal structure was observed across the series. Nevertheless for x = 0.35 and 0.40 a stoichiometric admixture of the hexagonal, MgZn 2 -type, P6 3 /mmc was evidenced. 57 Fe Mössbauer effect measurements for the series were performed at 4.2 K. The magnetic hyperfine fields form a separate branch of the Slater-Pauling curve. This branch is compared to the magnetic hyperfine field previously obtained for the Dy(Mn 0.4 Fe 0.6−x Al x ) 2 series (the Fe/Al substitution). The possible 3d electron band structure is discussed qualitatively within the Stoner model.
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Results of measurements of the magnetic susceptibility, the electrical resistivity, the crystal and electronic structures of the polycrystalline intermetallic compounds Dy(Co 1Àx Fe x) 2 (with x ¼ 0; 0.05; 0.10; 0.15; 0.20) are presented. The dependence of the Curie temperature T C and the lattice parameter a versus concentration x of the Fe element are established. The effect of the partial substitution Co by Fe is reflected in a change of T C (x), in the temperature dependence of the electrical resistivity and in the magnetization as a function of externally applied magnetic field. The electronic structure of the investigated system was studied by using X-ray photoemission spectroscopy (XPS). The obtained results show that the valence bands are dominated mainly by the Dy 4f and hybridized Fe/Co 3d states. The position and shape of the 3d bands depends clearly on the composition.
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Nukleonika
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Magnetic and Crystallographic Structure of Y₆Mn₂₃D₂₃
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The magnetic behavior of Y6Mn23 is dramatically altered upon hydrogenation (or deuteration). In this study it has been found, by means of high-resolution powder diffraction and Rietveld refinement techniques, that the crystallographic structure is distorted from face-centered cubic (Fm3m) at 295 K to a primitive tetragonal structure at 4 K in which deuterium atoms are atomically ordered. Y6Mn23 is a ferromagnetic compound with Tc=486 K, and bulk magnetization of 13.2 Bf.u. (formula unit). After deuteration of Y6Mn23 to the composition Y6Mn23D23, low-temperature scattering data (T\u3c180 K) show that the b and f2 sites in the Fm3m structure are antiferromagnetic and the d and f1 sites have no spontaneous magnetic moment. © 1984 The American Physical Society
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The single-phase intermetallic compounds of refractory metal Nb doped Dy 2 Fe 17 À x Nb x were prepared by arc melting. The substitution of Nb in the Dy 2 Fe 17 compound was found to have an important effect on their structure and magnetic properties. The Rietveld analysis of X-ray diffraction data shows that Dy 2 Fe 17 À x Nb x (x ¼0-1.5) solid solutions crystallize with the Th 2 Ni 17 structure. The lattice parameters obtained from Rietveld refinement show that the unit cell volume of Dy 2 Fe 17 À x Nb x increases linearly with increasing Nb concentration up to x ¼1. The solubility of Nb was found to be limited to x $ 1. The substitutional Nb atoms occupied all four sites in the order 12j412k 46g 44f of a Th 2 Ni 17 structure. The Curie temperature (T c) was found to be Nb content dependent. The T c first increased and then decreased with increasing Nb content x, attaining a maximum value of 460 K at around x ¼1, which is 78 K higher than that of Dy 2 Fe 17. The saturation magnetization decreased linearly with increasing Nb content from 69 emu/g for x ¼ 0 to 38 emu/g for x ¼1.5. 57 Fe Mössbauer spectra show the presence of DyFe 3 and NbFe 2 phases at a higher Nb content x Z 1. The hyperfine field values of 4f site first increased up to x ¼ 1 and then decreased at higher Nb content.
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