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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: Synthesis and X-ray analysis (300 K) of a new series were performed. The lattice parameter is considerably reduced with x. Electrical resistivity for the intermetallic series was measured in a wide temperature range and the parameters characterising the dependence of resistivity on temperature and composition were determined. The magnetic part of the resistivity was used to estimate Curie temperatures. The Curie temperature is strongly increased as a result of Mn/Co substitution. The obtained -results are related to the data known for the and series. [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 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: 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]

The structural and physical properties of nickel-diluted Tb 0.27 Dy 0.73 ( Fe 0.7 − x Ni x Co 0.3 ) 2 intermetallics were studied by X-ray diffraction, four-probe dc electrical measurements and standard strain gauge method. X-ray analysis shows that all samples crystallize in a cubic Laves structure. The lattice parameter decreases linearly with the nickel content. Electrical resistivity was measured in a temperature range of 15–1100 K. The parameters involved in the dependence of resistivity on temperature and composition were determined. Residual, phonon and magnetic resistivity were separated from the electrical resistivity using both the Matthiessen and Bloch-Grüneisen formulas. The compounds’ Curie temperatures, which decrease nonlinearly with x , were obtained from the magnetic resistivity curves. The maximum values of magnetostriction attained for the Tb 0.27 Dy 0.73 ( Fe 0.6 Ni 0.1 Co 0.3 ) 2 compound exceed about 851 ppm. Electronic 3d-band structure and magnetic moment calculations were performed using the Full-Potential Linearized Augmented Plane Waves method. The distribution function for the densities of 3d-states was used to characterise the transition metal subbands. [ABSTRACT FROM AUTHOR]

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]

Abstract: Findings from X-ray powder diffraction measurements (295 K) show that the cubic, -type, crystal structure appears in compounds.The lattice parameter is considerably reduced with x. Electrical resistivity for the intermetallic series was measured in a wide temperature range and the parameters characterising the dependence of resistivity on temperature and composition were determined. The magnetic part of the resistivity was used to estimate Curie temperatures. The Curie temperature is strongly reduced as a result of Fe/Ni substitution. The obtained -results are related to the data known for the and series. [Copyright &y& Elsevier]