Effect of Co on the Magnetic Properties of YGdFe $_17 rm - rm x$ Co $_rm x$ Ga
TL;DR: The structural and magnetic properties of YGdFe17-xCo x Ga (x=0,1,2 and 3) have been investigated through X-ray diffraction and magnetization studies.
Abstract: The structural and magnetic properties of YGdFe17-xCo x Ga (x=0,1,2 and 3) have been investigated through X-ray diffraction and magnetization studies. All the compounds up to x=0.2 are formed in a single-phase, hexagonal structure. The unit cell volume decreased with the addition of Co due to the smaller size of Co than that of Fe. The magnetization and Curie-temperature values are found to increase with the addition of x and could be due to the additional Co-Co, Fe-Co exchange whose magnitude is larger compared to that of Fe-Fe exchange. Magnetically aligned sample powders indicate the presence of planar anisotropy for all the compounds
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TL;DR: The effect of transition metal substitution for Fe and the structural and magnetic properties of Gd2Fe16Ga0.5TM 0.5 (TM = Cr, Mn, Co, Ni, Cu, and Zn) compounds were investigated in this article.
Abstract: The effect of transition metal substitution for Fe and the structural and magnetic properties of Gd2Fe16Ga0.5TM0.5 (TM = Cr, Mn, Co, Ni, Cu, and Zn) compounds were investigated in this study. Rietveld analysis of X-ray data indicates that all the samples crystallize in the hexagonal Th2Ni17 structure. The lattice parameters a, c, and the unit cell volume show TM ionic radii dependence. Both Ga and TM atoms show preferred site occupancy for 12j and 12k sites. The saturation magnetization at room temperature was observed for Co, Ni, and Cu of 69, 73, and 77 emu/g, respectively, while a minimum value was observed for Zn (62 emu/g) doping in Gd2Fe16Ga0.5TM0.5. The highest Curie temperature of 590 K was observed for Cu doping which is 15 and 5% higher than Gd2Fe17 and Gd2Fe16Ga compounds, respectively. The hyperfine parameters viz. hyperfine field and isomer shift show systematic dependence on the TM atomic number. The observed magnetic and Curie temperature behavior in Gd2Fe16Ga0.5TM0.5 is explained on the basis of Fe(3d)-TM(3d) hybridization. The superior Curie temperature and magnetization value of Co-, Ni-, and Cu-doped Gd2Fe16Ga0.5TM0.5 compounds as compared to pure Gd2Fe17 or Gd2Fe16Ga makes Gd2Fe16Ga0.5TM0.5 a potential candidate for high-temperature industrial magnet applications.
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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.
1,059 citations
"Effect of Co on the Magnetic Proper..." refers result in this paper
...in a relatively less effective way resulting in smaller changes in the values of and in these compounds compared to the former ones [5], [6]....
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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.
500 citations
TL;DR: In this paper, a simple model of magnetism for transitional metals is proposed, which is somewhat intermediate between Heisenberg's atomic model and Stoner's band model, and is shown to produce localized magnetic moments, by attracting locally the (traveling) electrons of one spin direction at the expense of the others.
Abstract: This paper suggests a simple model of magnetism for transitional metals which is somewhat intermediate between Heisenberg's atomic model and Stoner's band model. Starting with a paramagneticd band, described in the tight-binding approximation and with equal population of both spin directions, exchange interactions are introduced. They are shown able to produce localized magnetic moments, by attracting locally the (traveling) electrons of one spin direction at the expense of the others. A simple condition is obtained for such magnetic moments to appear spontaneously; it is shown to be fulfilled in many transitional metals. With the use of general results obtained recently by the authors and by others, it is then shown that each of these magnetic moments, if produced alone, should extend over a certain region in space, and should be surrounded by “fringes” of spin polarization with an alternating sign. The size of the central region and the wavelength of the fringes are related to an average wavelength of the Fermi electrons, and thus to the filling of the d band. The sign and the strength of the coupling between magnetic moments centered on neighboring atoms is deduced from the extent of their overlap. The magnetic couplings observed in the first transitional series are shown to be in fair agreement with this model. The conditions prevailing in the other series and in alloys are also discussed. This model is compared to those put forward by Zener, Yoshida, and Slater. It is emphasized that it leads to the equivalent of chemical exchange integrals between the moments of neighboring atoms without losing the characteristic features of the d band, especially its high electronic specific heat and Pauli paramagnetism.
89 citations
"Effect of Co on the Magnetic Proper..." refers background in this paper
...This increase in values can also be explained on the basis of Friedel model [9], in which the interaction between two magnetic moments would be strong and ferromagnetic if the distance “ ” between them is smaller than the distance “ ” covered by the main peak of the Friedel oscillations, i....
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TL;DR: The effect of Ga substitution for Fe in R2Fe17 (R=Y, Sm, Gd, Tb, Dy, Ho, Er, and Tm) compounds on the structure and magnetocrystalline anisotropy has been studied by means of x-ray diffraction and magnetization measurements as discussed by the authors.
Abstract: The effect of Ga substitution for Fe in R2Fe17 (R=Y, Sm, Gd, Tb, Dy, Ho, Er, and Tm) compounds on the structure and magnetocrystalline anisotropy has been studied by means of x‐ray diffraction and magnetization measurements. Both iron sublattice anisotropy and rare earth sublattice anisotropy are found to be modified by the introduction of the gallium atoms. A uniaxial anisotropy is shown in R2Fe17−xGax (for R=Y, Gd, Tb, Dy, Ho, Er, and Tm) compounds with high Ga concentration, whereas a reversal change in the easy magnetization direction is observed in the samples for R=Sm. The contributions to the uniaxial orientation of the magnetization in these compounds result from not only the rare earth sublattice, but also the iron sublattice.
61 citations
"Effect of Co on the Magnetic Proper..." refers background in this paper
...Partial substitution of nonmagnetic elements such as Al, Ga, and Si for iron has been reported to cause considerable increase in the and magnetocrystalline anisotropy of these compounds [2], [3]....
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TL;DR: In this paper, the effect of Al substitution in Nd2Fe17 compound by means of first-principles calculations was studied, and it was shown that the Al moment is oppositely polarized to Fe.
Abstract: We have studied the effect of Al substitution in Nd2Fe17 compound by means of first‐principles calculations. We first obtain the site‐decomposed potentials for Fe from self‐consistent calculation on Y2Fe17 and the atomiclike potentials in the crystalline environment for Al and Nd. Calculations are carried out for a single Al substituting one Fe at four different Fe sites (6c), (9d), (18f ), and (18h), two Al substituting two Fe (18h), and four Al substituting three Fe (18h) and one Fe (18f ). Our results show that the Al moment is oppositely polarized to Fe. The average moment per Fe atom actually increases for Al substituting Fe (18h) and Fe (18f ) is about the same for Al substituting Fe (6c), and is drastically reduced when replacing Fe (9d). Experimentally, Al is shown to be excluded from the (9d) sites because of the small Wigner–Seitz volume. When two Fe atoms are replaced by two Al atoms, the total moment is only slightly less than when only one Fe atom is replaced, and the Ms per Fe site actually ...
24 citations
"Effect of Co on the Magnetic Proper..." refers background in this paper
...Interstitial modification by N/C is known to improve the as well as the magnetocrystalline anisotropy in these compounds [4]....
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