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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]

Abstract: Electrical resistivities of the Dy(Fe1−x Co x )2 intermetallic series were measured in a wide temperature region and the residual, phonon and magnetic contributions to the resistivities across the series were determined. The magnetic ordering temperatures were estimated for the Dy(Fe1−x Co x )2 compounds using the magnetic contribution to the electrical resistivity. The splitting energies between the 3d subbands of iron for the Dy(Fe1−x Co x )2 series were estimated using the magnetic hyperfine fields at 57Fe nuclei. The Curie temperatures obtained for the Dy(Fe1−x Co x )2 intermetallics and the Curie temperatures reported in the literature for the Dy(Mn1−x Fe x )2 and Dy(Mn0.4−x Al x Fe0.6)2 series correlate linearly with the squared energy splitting between the 3d subbands. [Copyright &y& Elsevier]

Abstract: Electrical resistivity measurements for the Dy(Mn0.4−x Al x Fe0.6)2 intermetallics were performed in a wide temperature region and the parameters characterising the resistivity dependence on temperature were determined. Mössbauer effect studies were performed in the temperature range around the Curie temperatures. From both the methods the magnetic ordering temperatures were estimated. For the Dy(Mn0.4−x Al x Fe0.6)2 and Dy(Mn1−x Fe x )2 series the splitting energies between the 3d subbands were estimated. It was found that the Curie temperatures obtained for the Dy(Mn0.4−x Al x Fe0.6)2 intermetallics and the Curie temperatures reported in the literature for the Dy(Mn1−x Fe x )2 series correlate linearly with the squared energy splitting between the 3d subbands. [Copyright &y& Elsevier]

Abstract: Electrical resistivity studies performed in a wide temperature range across the complete Fe/Co substituted Tb0.27Dy0.73(Fe1−x Co x )2 intermetallic series, with a borderline compound Tb0.27Dy0.73Fe2 known as Terfenol-D are presented. Parameters characterizing the dependence of resistivity on temperature, including the Debye temperature, are determined. Residual, phonon and magnetic contributions are separated from electrical resistivity. The magnetic contribution to electrical resistivity is applied to estimate Curie temperatures. Regions of weak and strong ferromagnetism of the transition metal sublattice are evidenced. The Curie temperature increases with x, approaches a maximum for x = 0.3 and reduces across the rest of the series. Some results of electronic band structure calculations using the Full-Potential Linearized Augmented Plane Waves (FLAPW) method are also presented. A distribution function for the densities of 3d states is introduced and a formula to estimate the band splitting energy is proposed. The obtained 3d and 4s band splitting energies for iron, cobalt and average for transition metal are presented. The Curie temperature across the Tb0.27Dy0.73(Fe1−x Co x )2 system is described using a formula relating to both the FLAPW calculated magnetic moments and the statistical properties of the substituted transition metal sublattice. [Copyright &y& Elsevier]

Abstract: X-ray powder diffraction measurements (295K) show that the cubic, MgCu2-type, crystal structure appears in compounds. The lattice parameter is considerably and weakly nonlinearly reduced with x. The electrical resistivities of the intermetallic series were measured over a wide temperature range and the parameters characterising the dependence of resistivity on temperature and composition were determined. In order to separate the residual, phonon and magnetic contributions to total resistivity the Matthiesen formula was used. The magnetic part of the resistivity was used to estimate Curie temperatures. The Curie temperature is strongly and nonlinearly reduced as a result of Co/Ni substitution. The obtained results are related to data known for the and series. [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: From X-ray analysis (295 K) it was found that the cubic, -type, crystal structure appears across the Gd(Fe1−x Co x )2 series. Electrical resistivity measurements for the Gd(Fe1−x Co x )2 intermetallics were performed in a wide temperature region and the parameters characterizing the resistivity dependence on temperature and composition were determined. The differential of the electrical resistivity against temperature was used to estimate Curie temperatures. The Curie temperature versus x, high and moderately increasing in the iron-rich area, rapidly drops in the cobalt-rich region. The obtained results are compared with the data known for the Dy(Fe1−x Co x )2 series. The Curie temperature is related to both the number of 3d electrons and the de Gennes factor. [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]