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Abstract: The consequences of Fe/Ni substitution in Tb 0.27 Dy 0.73(Fe 1−x Nix )2 intermetallics, with a starting compound Tb 0.27 Dy 0.73 Fe 2 known as Terfenol – D, were studied. Ni substitution introduces a local area, at sub-nanoscale, with different Fe/Ni neighbourhoods of the 57Fe atoms. 57Fe Mössbauer effect measurements for the intermetallic system Tb 0.27 Dy 0.73(Fe 1−x Nix )2 carried out at 4.2 K evidence an [100] easy axis of magnetization. Hyperfine interaction parameters – an isomer shift, a magnetic hyperfine field and a quadrupole interaction parameter – were determined from the fitting procedure of the spectra, both for the local neighbourhood area and, as averaged values, for the sample as bulk. As a result of Fe/Ni substitution, a Slater–Pauling type dependence for the average magnetic hyperfine field vs. Ni content is observed. Electronic band structure calculations using the Full-Potential Linearized Augmented Plane Waves (FLAPW) method were performed. The relation between the experimentally determined magnetic hyperfine field and the weighted magnetic moment calculated per transition metal atom is discussed. [ABSTRACT FROM AUTHOR]

Abstract: This paper concerns synthesis, X-ray analysis (300K), electrical resistivity and 57Fe Mössbauer effect studies (4.2K) of complete Tb0.27Dy0.73(Mn1−x Fe x )2 intermetallic series, with a borderline compound Tb0.27Dy0.73Fe2 known as Terfenol-D. A cubic Laves phase Fd3m of the MgCu2-type is observed across the series. The lattice parameter decreases parabolically with x. Electrical resistivity was measured in a wide temperature region across the Tb0.27Dy0.73(Mn1−x Fe x )2 series and the parameters which characterize resistivity dependence on temperature, including Debye temperature, were determined. Residual, phonon and magnetic contributions were separated from electrical resistivity. The magnetic contribution to electrical resistivity was applied to estimate Curie temperatures. The Curie temperature increases significantly with x. 57Fe Mössbauer effect measurements for the Tb0.27Dy0.73(Mn1−x Fe x )2 intermetallic system evidence an [100] easy axis of magnetization. Mn/Fe substitution introduces a local area, at sub-nanoscale, with different Mn/Fe neighbourhoods of the tested 57Fe atoms. Hyperfine interaction parameters, an isomer shift, a magnetic hyperfine field and a quadrupole interaction parameter were determined from the spectra both for the local neighbourhood area and, as averaged values, for the sample as bulk. The average magnetic hyperfine field increases parabolically with x. The correlation between Curie temperatures and magnetic hyperfine fields is discussed. [ABSTRACT FROM AUTHOR]

Abstract: A consequence of Co/Ni substitution in the intermetallics Dy(Fe0.4Co0.6−x Ni x )2 was tested in this paper. Mössbauer effect measurements for the intermetallic system were carried out at 4.2K and the determined hyperfine interaction parameters as functions of composition are reported. The magnetic hyperfine field as well as the Curie temperature is strongly reduced with a composition parameter x. Band structure calculations using the full-potential linearized augmented plane waves (FLAPW) method were performed. Some properties of the 3d bands of the Fe, Co and Ni constituents are discussed. The 3d band splitting energies and the magnetic moments of transition metals reduce with x. The experimentally determined magnetic hyperfine field correlates linearly with the calculated stoichiometrically weighted magnetic moment of 3d atoms and correlates linearly with the weighted splitting energy between 3d subbands. The Curie temperature changes nonlinearly with the squared magnetic hyperfine field or with the calculated squared weighted splitting energy between 3d subbands. [Copyright &y& Elsevier]

It was previously found that the magnetic hyperfine fields observed at 57Fe nuclei (4.2 K) in the Dy(Mn1-xFex)2 and Dy(Fe1-xCox)2 intermetallics form a Slater–Pauling curve. Both 3d subbands in the Dy(Mn0.4Fe0.6)2 compound are filled up only partially with 3d electrons. The consequence of Mn/Al substitution, in the Dy(Mn0.4Fe0.6)2 compound was studied in the present paper. For this purpose the synthesis and X-ray analysis (300 K) of the series Dy(Mn0.4-xAlxFe0.6)2 were performed. The cubic, MgCu2-type Fd3m crystal structure was observed across the series. Nevertheless for x=0.35 and 0.40 a stoichiometric admixture of the hexagonal, MgZn2-type, P63/mmc was evidenced. 57Fe 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(Mn0.4Fe0.6-xAlx)2 series (the Fe/Al substitution). The possible 3d electron band structure is discussed qualitatively within the Stoner model. [Copyright &y& Elsevier]

It was previously found that the magnetic hyperfine fields observed at 57Fe nuclei (4.2 K) in the Dy(Mn1−xFex)2 and Dy(Fe1−xCox)2 intermetallics form a Slater–Pauling curve with a maximum hyperfine field for the Dy(Fe0.7Co0.3)2 compound. The Fe/Al substitution in the Dy(Fe0.7Co0.3)2 compound was studied in the present paper. The intermetallic series Dy(Fe0.7−xAlxCo0.3)2 was prepared and data of an X-ray analysis are presented (300 K). The cubic, MgCu2-type, Fd3m crystal structure was observed. 57Fe Mo¨ssbauer effect measurements for the series were performed (4.2, 77, 293 K) and the obtained hyperfine parameters are presented. The magnetic hyperfine fields form a separate branch of the Slater–Pauling curve. The data related to a possible band structure are qualitatively discussed within the frame of the Stoner model. [Copyright &y& Elsevier]

The synthesis of materials and the studies of crystal structure and Fe Mössbauer effect were performed for TbDy(FeCo) intermetallics. Terfenol-D (TbDyFe) is the starting compound of this Fe/Co-substituted series. X-ray measurements showed evidence of a pure cubic Laves phase C15, MgCu-type, and unit cell parameters were determined across the series. A Co substitution introduced local area, at sub-nanoscale, with random Fe/Co neighbourhoods of the Fe atoms. Mössbauer effect spectra for the TbDy(FeCo) series at room temperature are composed of a number of locally originated subspectra due to the random distribution of Fe and Co atoms in the transition metal sublattice, and due to [1 1 1] an easy axis of magnetization. Isomer shift, magnetic hyperfine field and quadrupole interaction parameter were obtained from the spectra, both for the local area and for the bulk sample. As a result of Fe/Co substitution, a Slater-Pauling-type curve for the average magnetic hyperfine field vs. Co content was observed. It was found that the magnetic hyperfine fields corresponding to the local area also create a dependence of the Slater-Pauling-type vs. Co contribution in the Fe/Co neighbourhoods. [ABSTRACT FROM AUTHOR]

Abstract: The after-effects of Fe/Co substitution in the intermetallic series , with a starting compound known as Terfenol-D, were studied. Co substitution introduces a local area, at sub-nanoscale, with random Fe/Co neighbourhoods of the atoms. Mössbauer effect measurements for the intermetallic system carried out at 4.2K evidence an easy axis of magnetization. Hyperfine interaction parameters: isomer shift, a magnetic hyperfine field and a quadrupole interaction parameter were obtained from the fitting procedure of the spectra, both for the local area and for the sample as bulk. As a result of Fe/Co substitution, a Slater–Pauling type curve for the average magnetic hyperfine field vs. Co content is observed. It is found that the magnetic hyperfine fields corresponding to the local area sorted out against Co contribution in the Fe/Co neighbourhoods also create a dependence similar to a Slater–Pauling type curve. Band structure calculations using the Full-Potential Linearized Augmented Plane Waves (FLAPW) method were performed. The experimentally determined magnetic hyperfine field correlates linearly with the weighted magnetic moment calculated per transition metal atom. [Copyright &y& Elsevier]

Abstract: A consequence of Fe/Ni substitution in the intermetallics Dy(Fe0.7−x Ni x Co0.3)2 was tested in this paper. Mössbauer effect measurements for the intermetallic system were carried out at 4.2K. The obtained hyperfine interaction data are presented. The magnetic hyperfine field as well as the Curie temperature is strongly reduced with a composition parameter x. Band structure calculations using the Full-Potential Linearized Augmented Plane Waves (FLAPW) method were performed. The experimentally determined magnetic hyperfine field correlates linearly with the weighted magnetic moment calculated per transition metal atom and correlates linearly with the average splitting energy between 3d subbands. The Curie temperature changes in an approximate linear fashion with the squared magnetic hyperfine field or with the calculated squared splitting energy between 3d subbands. [Copyright &y& Elsevier]

Abstract: This paper looks at synthesis, electrical resistivity and Mössbauer effect studies on intermetallic compounds . Cubic Laves phase of MgCu2-type were observed across the series. The lattice parameters linearly increase with Gd concentration and the lattice parameters of the intermetallics series are compared to data previously observed for the series (R=Y, Dy, Gd) and series (M=Fe, Co). Electrical resistivity for the intermetallic series was measured in the temperature range 15–1100K. Parameters characterizing the resistivity dependence on temperature were determined. Residual, phonon and magnetic resistivity were separated from the measured electrical resistivity using both the Matthiesen formula and the Bloch–Gruneisen formula. Curie temperatures of the studied series were determined using both electrical resistivity and Mössbauer effect measurements, with the Mössbauer effect measured in the temperature range around the magnetic ordering temperature. The Curie temperature increases with x. The obtained Curie temperatures for the are similar to data known for the series (R=Y, Dy, Gd) and series (M=Fe, Co). [Copyright &y& Elsevier]

Abstract: Synthesis, X-ray analysis (300K), electrical resistivity and Mössbauer effect studies in the intermetallic compounds Y(Fe1−x Co x )2 are reported. Cubic Laves phases MgCu2-type, were observed across the series. Crystal lattice parameter is considerably reduced with Co concentration. The lattice parameters of the Y(Fe1−x Co x )2 series are compared to analogous data previously observed for the Gd(Fe1−x Co x )2 and Dy(Fe1−x Co x )2 series. Electrical resistivity for the Y(Fe1−x Co x )2 intermetallic series was measured in the temperature range 15–1000K. Parameters characterizing the resistivity dependence on temperature including Debye temperature were determined. Residual, phonon and magnetic resistivity were separated from the measured electrical resistivity. Curie temperatures of the Y(Fe1−x Co x )2 series were determined using both electrical resistivity and Mössbauer effect measurements. The Curie temperature increases with x, reaches maximum approximately at x =0.3 and than strongly decreases as a result of Fe/Co substitution. The obtained Curie temperatures for the Y(Fe1−x Co x )2 series are related to the data known for the Dy(Fe1−x Co x )2, Gd(Fe1−x Co x )2 and other series. Numerical formula, which approximates Curie temperatures of intermetallics is proposed. [Copyright &y& Elsevier]