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The structural and magnetoelastic properties of polycrystalline samples of Y3Fe27.2Cr1.8 and Ce3Fe25Cr4 intermetallic compounds are investigated by means of X-ray diffraction, thermomagnetic, thermal expansion and magnetostriction measurements in the temperature range of 77-500 K under applied magnetic fields up to 1.5 T. The well defined anomalies observed in the linear thermal expansion coefficient curves are associated with the magnetic phase transitions and presence of small amounts of 1:12 phase in the Ce3Fe25Cr4 sample; the latter is also confirmed by AC susceptibility measurements. For Y3Fe27.2Cr1.8, saturation behavior is observed in the anisotropic magnetostriction isotherms near the magnetic ordering temperature (TC), whereas for Ce3Fe25Cr4 compound, saturation starts well below TC. The additional anomalies observed in the volume magnetostriction isotherms of both compounds are explained based on the anisotropy field in the a-b plane and along the c-axis of the unit cell. [ABSTRACT FROM AUTHOR]

Abstract: The thermal expansion and magnetostriction of Nd2Fe14Si3 polycrystalline intermetallic compound was measured, using the strain gauge method in the temperature range 77–590K under applied magnetic fields up to 1.5T. Results show that both linear thermal expansion and linear thermal expansion coefficient exhibit anomalies below Curie temperature. A pronounced positive spontaneous volume magnetostriction has been observed below the Curie temperature. The spontaneous volume magnetostriction decreases with Si substitution in Nd2Fe17 compound. The saturation trend of the anisotropic magnetostriction below 115K depends on the saturation of the λγ mode. In the low field region (μ0H<0.3T), a minimum appears in the isothermal curves of the volume magnetostriction that may be attributed to the domain walls motion and rotation of the magnetic moments of domains toward the applied field direction. The results of the spontaneous and anisotropic magnetostriction are discussed based on the local magnetic moment model and irreducible magnetoelastic coupling modes, respectively. [Copyright &y& Elsevier]

Abstract: In this work, The magnetoelastic properties of polycrystalline samples of Tb3 (Fe28−x Co x ) V1.0 (x=0, 3, 6) intermetallic compounds are investigated by means of linear thermal expansion and magnetostriction measurements in the temperature range of 77–515K under applied magnetic fields up to 1.5T. The linear thermal expansion increases with the Co content. The well-defined anomalies observed in the linear thermal expansion coefficients for Tb3 (Fe28−x Co x ) V1.0 (x=0, 3, 6) compounds are associated with the magnetic ordering temperature for x=0 and spin reorientation temperatures for x=3, 6. Below transition temperatures, the value of the longitudinal magnetostriction (λ Pa) at 1.6T increases with Co content. [Copyright &y& Elsevier]

Abstract: Magnetoelastic properties of the Pr6Fe11Ga3 alloy are studied by magnetostriction and thermal expansion measurements. The effects of short- and long-range magnetic ordering processes about Curie temperature clearly appear in the temperature dependence of the spontaneous magnetostriction as two increasing steps with decreasing temperatures. Thermal variations of the total magnetocrystalline anisotropy introduce pronounce changes in the isofield curves of the forced magnetostriction as a negative minimum below 200K, a compensation phenomena about 250K, and a positive maximum between 250K and T c=320K. The observed behavior of magnetostriction is discussed in terms of the competitive anisotropies of Pr and Fe sublattices and coupling magnetostrictive constants. [Copyright &y& Elsevier]

In this research the effect of partial replacement of Nd by Dy atoms on magnetoelastic properties of Nd2Fe14C (2-14-1) alloys is studied by magnetostriction measurement of Nd2−xDyxFe14C with x=0.1, 0.3, 0.5 samples at 77 K up to 300 K temperatures. Spin re-orientation temperature, Tsr, is also determined by measuring temperature dependence of magnetic susceptibility in this range. Results show that spin re-orientation temperature increases rapidly with increasing Dy content up to x=0.3. But, Tsr was not affected with higher Dy substitution, substantially. Magnetostriction results show that the partial substitution of Dy increases the anisotropic magnetostriction, which is attributed to stronger magnetocrystalline anisotropy. Dy partial substitution also changes magnetoelastic energy of the two spin phases of high and low temperatures. Increasing x causes the single particle contribution in magnetoelastic energy of low-temperature phase to increase rapidly, so that Callens theory would be sufficient for describing observed temperature dependence of magnetostriction. In addition, partial substitution of Dy with x=0.3 and 0.5 causes a rapid increase in volume magnetostriction after Tsr, i.e. in the high-temperature phase. This rapid increase in volume magnetostriction indicates that the exchange interaction contribution in the magnetoelastic energy is promoted at the high-temperature phase by Dy substitution. [Copyright &y& Elsevier]

In this research, we have studied magnetoelastic interactions in Nd6Fe13Si solid solution by magnetostriction and thermal expansion measurements. Magnetostriction versus temperature in the range of 77–300 K show that by rising temperature above 115 K, the sign of magnetostriction changes from negative to positive, which indicates a rapid expansion of the sample. This sign reversing is accompanied by a spin re-orientation of iron ions from basal plane of tetragonal unit cell to c-axis at higher temperatures. At the spin re-orientation temperature (Tsr) of 115 K, where the two spin arrangements coexist with equal probability, magnetostriction remains around zero. This is due to the compensation of the negative magnetostriction of the low-temperature phase by positive magnetostriction of the high-temperature phase. The magnetostriction compensation effect appears as a peak in the thermal expansion coefficient curve. [Copyright &y& Elsevier]

Abstract: The thermal expansion and magnetostriction of HoFe11−x Co x Ti (x=0, 0.3, 0.7 and 1) intermetallic compounds were measured, using the strain gauge method in the temperature range 77–590K under applied magnetic fields up to 1.5T. Results show that for samples with x=0 and 0.3, both linear thermal expansion and linear thermal expansion coefficient exhibit anomalies below the Curie temperature. Below room temperature, the spontaneous volume magnetostriction decreases with Co content. For all compounds studied, the anisotropic magnetostriction shows similar behaviour in the measured temperature range. The magnetostriction compensation occurs above room temperature in all samples. The volume magnetostriction shows a linear dependence on the applied field and by approaching the Curie temperature this trend changes to parastrictive behaviour. The results of the spontaneous magnetostriction are discussed based on the local magnetic moment model. The contribution of magnetostriction attributed to the magnetic sublattices R and T (Fe or Co) is discussed. [Copyright &y& Elsevier]

Abstract: The thermal expansion and magnetostriction of polycrystalline sample of the ErMn6Sn6 intermetallic compound with hexagonal HfFe6Ge6-type structure are investigated in the temperature range of 77K to above 400K. The thermal expansion measurement of the sample shows anomalous behavior around its T N=340K. The isofield curves of volume magnetostriction also reveal anomalies at paramagnetic–antiferromagnetic and antiferromagnetic–ferrimagnetic phase transitions. In the antiferromagnetic state, the transition to ferrimagnetism can be induced by an applied magnetic field. The threshold field for the metamagnetic transition H th increases from 0.18T at 84K to about 1T around 220K, and then decreases monotonously to T N. This behavior is well consistent with that observed earlier on magnetization curves attributed to exchange-related metamagnetic transition rather than the anisotropy-related one. Furthermore, the low H th values suggest that the Mn–Mn coupling in ErMn6Sn6 is not so strong. The experimental results obtained are discussed in the framework of two-magnetic sublattice by bearing in mind the lattice parameter dependence of the interlayer Mn–Mn exchange interaction in this layered compound. From the temperature dependence of magnetostriction values and considering the magnetostriction relation of a hexagonal structure, we attempt to determine the signs of some of the magnetostriction constants for this compound. [Copyright &y& Elsevier]

Abstract: The thermal expansion and spontaneous magnetostriction of polycrystalline samples of Er1−xGdxMn6Sn6 (0 ≤ x ≤ 1) intermetallics with hexagonal HfFe6Ge6-type structure are investigated in the temperature range of 77–520 K. The Gd substitution has significant effect on the interatomic distances and especially on inter-sublattice R–Mn couplings. The replacement of Er by Gd causes the lattice constants to increase due to the larger atomic radius of Gd compared with Er. It also results in increasing the ordering temperature as well as the spontaneous magnetostriction values following reinforcement the R–Mn coupling. The examined samples exhibit considerable thermal expansion anomalies at the Néel temperature (TN  = 340 and 335 K for the samples with x = 0 and 0.2, respectively) and also at TM  = 309–311 K where the Mn moments experience collapse-like reduction. Whereas, trivial anomalies are revealed at the Curie points (TC  = 77 K for the sample with x = 0, 164 and 383 K for x = 0.2, 419 and 434 K for x = 0.6 and 1, respectively). From the results, it is concluded that the magnetovolume effects in these compounds originate mainly from the antiferromagnetic interlayer Mn–Mn exchange interactions, and the intraplane ferromagnetism does not influence the magnetoelasticity. [Copyright &y& Elsevier]

Abstract: Magnetoelastic properties of Nd6Fe13Cu intermetallic compound are reported. To study the magnetoelastic behaviour of this compound, the thermal expansion as well as the longitudinal (λ l) and transverse (λ t) magnetostriction were measured by using the strain gauge method in the selected temperature range of 80–500K under applied magnetic fields up to 1.5T. An anomaly and invar-type effects are observed in the linear thermal expansion and α(T) curves at the Néel temperature. The linear spontaneous magnetostriction decreases sharply by approaching the Néel temperature and also shows the short-range magnetic ordering effects when antiferromagnetic–paramagnetic transition occurs. In the low field region, the absolute values of the anisotropic magnetostriction are small and then start to increase with applied magnetic field. Each isofield curve of the anisotropic magnetostriction passes through a minimum and then approaches to zero with increasing temperature. This magnetostriction compensation arises from the difference in the magnetoelastic coupling constants of the sublattices in this compound. [Copyright &y& Elsevier]

Abstract: We studied the thermal expansion and magnetostriction of polycrystalline samples of GdMn6Sn6 intermetallic compound with hexagonal HfGe6Fe6-type structure in the temperature range of 77–520K. The thermal expansion measurement of the sample shows anomalous behavior around its T C=434K and T M=309K, possibly the point of collapse-like reduction of Mn moments. In addition, the isofield curves of anisotropic and volume magnetostriction reveal anomalies around paramagnetic to ferrimagnetic phase transition. The obtained experimental results are discussed in the framework of two-magnetic sublattices by bearing in mind the lattice parameter dependence of interlayer Mn–Mn exchange interaction in this layered compound. From the temperature dependence of magnetostriction values and considering the magnetostriction relation of a hexagonal structure, we attempt to determine the signs of some of the magnetostriction constants as well as a comparison of their orders of magnitude for this compound. [Copyright &y& Elsevier]

Abstract: We studied the effect of Co substitution in Nd6Fe13−x Co x Si (x = 0, 1) intermetallic compounds on the crystalline structure, magnetic properties and thermal expansion. The partial Co substitution reduces the lattice parameters of the tetragonal Nd6Fe13Si structure which enhance (3d–3d) exchange interaction and this causes an increase of the Néel temperature (TN ). The spin reorientation temperature (TSR ) of Nd6Fe12CoSi occurs at a higher temperature with respect to that of the Nd6Fe13Si compound. Both the linear thermal expansion and the linear thermal expansion coefficient α(T) show remarkable anomalies at TSR and the magnetic ordering temperature (TN ). TSR is associated with a shoulder in the linear thermal expansion and near TN we observe invar-type of behaviour. Both effects are enhanced for the Co substituted sample, giving clear evidence for the enhanced exchange interactions. [Copyright &y& Elsevier]

Abstract: The magnetostriction and thermal expansion of Er2Fe14−x Co x B (x =1, 3 and 5) intermetallic compounds were measured, using the strain gauge method in the temperature range 75–450K under applied magnetic fields up to 1.5T. For all samples the longitudinal magnetostriction (λ l) undergoes an anomaly around the spin reorientation temperature (T SR). It is also observed that λ l decreases with increasing the Co content. All compounds show saturation type behaviour in their anisotropic magnetostriction curves at different temperatures and applied fields. The saturation behaviour of the compound with x =3 occurs at higher temperatures than with x =1 and 5. The volume magnetostriction strongly increases below μ 0 H =0.3T, then monotonically rises with applied field up to the spin reorientation temperature. An invar type behaviour is observed above 200K in the compound with x =1. The results are discussed based on the temperature dependence of magnetocrystalline anisotropy of compounds below and above their T SR. [Copyright &y& Elsevier]