Effect of Al and Si substitutions on the magnetic properties of SmTbFe17
TL;DR: The structural and magnetic properties of SmTbFe17−xAlx (x=0-8) and SmtbFe 17−x6 (x = 0-3.5) were investigated by x-ray-diffraction and magnetization studies.
Abstract: The structural and magnetic properties of SmTbFe17−xAlx (x=0–8) and SmTbFe17−xSix (x=0–3.5) were investigated by x-ray-diffraction and magnetization studies. All the compounds stabilize in rhombohedral structure. The lattice parameters are found to increase with Al substitution whereas they are found to decrease with Si substitution. The rates of the decrease of saturation magnetization (Ms) value with the substitution of Al and Si are almost the same. The easy direction of magnetization (EMD) is in the ab plane up to an Al concentration of x=7 and has a tendency to shift towards the c axis at x=8. All the compounds with Si are seen to have the EMD in the ab plane. Electron-magnon scattering is seen to contribute to the electrical resistivity in both Al- and Si-substituted compounds; in the temperature range of 30–60K and at higher temperatures, scattering due to phonons is observed.
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TL;DR: In this paper, the R2Ni17 and R2Fe17C intermetallic compounds were found to absorb approximately two atoms of nitrogen per formula unit on heating in ammonia or nitrogen.
Abstract: The R2Fe17 and R2Fe17C intermetallic compounds are found to absorb approximately two atoms of nitrogen per formula unit on heating in ammonia or nitrogen. The interstitial nitrides retain the original Th2Ni17 or Th2Zn17 structures, but with a large increase in unit cell volume (≈ = 7%). Curie temperatures of 420 °C are found when R = Y and 470 °C when R = Sm. There are also substantial increases in magnetisation and anisotropy field (when R = Sm). These new interstitia nitrides have excellent intrinsic magnetic properties for permanent magnet applications.
1,026 citations
TL;DR: A review of the formation, the crystal structure and the magnetic properties of several classes of rare earth based intermetallic compounds that lend themselves as starting materials of permanent magnets is given in this article.
Abstract: A review is given of the formation, the crystal structure and the magnetic properties of several classes of rare earth based intermetallic compounds that lend themselves as starting materials of permanent magnets. These compounds include R2Fe14B, R2Fe14C and R2Co14B and the large class of ternary rare earth compounds having the tetragonal ThMn12 structure. Special emphasis is given to the changes in magnetic properties of R2Fe17 compounds observed after interstitial solution of C or N atoms. The magnetic properties of all these compounds are discussed in terms of current models based on intersublattice and intrasublattice exchange and the interplay between the rare earth sublattice anisotropy and 3D sublattice anisotropy. A substantial portion of the review is devoted to manufacturing routes of permanent magnets and a description of the coercivity mechanisms operative in the magnets. A comparison is made of the performance and economic costs of various types of magnets and novel applications are briefly discussed.
487 citations
TL;DR: In this article, the Curie temperature of Fe, Co and Ni as well as of their compounds with Y (including Y2Fe14B) are calculated by including the effects of spin fluctuations in the long wavelength limit via a renormalisation of Landau coefficients.
Abstract: The Curie temperature of Fe, Co and Ni as well as of their compounds with Y (including Y2Fe14B) are calculated by including the effects of spin fluctuations in the long wavelength limit via a renormalisation of Landau coefficients. The numerical values depend on the use of recent calculations of correlation effects and of the band structure. As a result, good agreement is found with the experimental values of TC of the materials covered.
148 citations
TL;DR: In this paper, an x-ray diffraction study of the substitution of gallium in Tb2Fe17 to form the Tb 2Fe17−xGax solid solutions indicates that the compounds adopt the rhombohedral Th2Zn17 structure.
Abstract: An x‐ray diffraction study of the substitution of gallium in Tb2Fe17 to form the Tb2Fe17−xGax solid solutions indicates that the compounds adopt the rhombohedral Th2Zn17 structure. The unit cell volume and the a‐axis lattice parameter increase linearly with increasing gallium content. The c‐axis lattice parameter increases linearly from x=0 to 6 and then decreases between x=7 and 8. Magnetic studies show the Curie temperature increases by ∼150° above that of Tb2Fe17 to reach a maximum between x=3 and 4, and then decreases with further increases in x. Neutron diffraction studies of Nd2Fe15Ga2 and Tb2Fe17−xGax, with x equal to 5, 6, and 8, indicate that the gallium completely avoids the 9d site, occupies the 6c ‘‘dumbell’’ site only at high values of x and strongly prefers the 18f site at high values of x. The magnetic neutron scattering indicates both that the terbium sublattice magnetization couples antiferromagnetically with the iron sublattice and that there is a change in easy magnetization direction f...
130 citations
TL;DR: In this article, the temperature and field dependence at 4.2 K of the magnetization of Y2Fe17−xAlx and Ho2Fe 17−xalx (x ≤ 10) compounds has been studied.
Abstract: The temperature and field dependence at 4.2 K of the magnetization of Y2Fe17−xAlx and Ho2Fe17−xAlx ( x ≤ 10) compounds has been studied. Coupling constants have been derived by analyzing both the temperature dependence and the field dependence of the magnetization with a mean-field model. The results are compared to each other. The influence of the Ho-Ho interaction is considered. There is no pronounced temperature dependence of the interaction constant between the rare-earth and transition-metal sublattice.
123 citations