The structure and magnetic properties of (x = 0-8) compounds with and Tb
TL;DR: In this article, the effect of Ga substitution for Co on the structure and magnetic properties of and compounds (x = 0, 1, 2, 3, 4, 5, 6, 7 and 8) was investigated.
Abstract: X-ray diffraction (XRD) and magnetic measurements were employed to investigate the effect of Ga substitution for Co on the structure and magnetic properties of and compounds (x = 0, 1, 2, 3, 4, 5, 6, 7 and 8). XRD patterns show that all samples are single phase with the hexagonal -type structure or the rhombohedral -type structure except the samples with x = 7 and 8 which contain a small amount of Co. The Ga substitution for Co in and compounds leads to a monotonic increase in unit cell volume and an approximately linear decrease in saturation magnetization. The Curie temperature is found to decrease rapidly with increasing Ga concentration. The compensation points are observed for the samples with x = 4, 5 and 6. The intersublattice-molecular-field coefficients, , have been deduced on the basis of magnetization curves at the compensation temperature. The exchange-coupling constants and have been calculated by analysing both the field dependence and the temperature dependence of the magnetization. It has been found that the substitution of Ga for Co in these compounds reduces the Co-Co exchange interaction, while it has little influence on the R-Co exchange interaction. It is noteworthy that the Ga substitution has not changed the room-temperature easy magnetization direction for both and compounds.
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TL;DR: In this article, the effect of Mn substitution for Co on the structure and magnetic properties of Y2Co17−xMnx compounds with x=0-8 was investigated. And the results showed that the substitution of Mn for Co led to a monotonic increase in unit cell volume.
Abstract: X-ray diffraction (XRD) and magnetization measurements were employed to investigate the effect of Mn substitution for Co on the structure and magnetic properties of Y2Co17−xMnx compounds with x=0–8. XRD patterns show that all samples are single phase with a hexagonal Th2Ni17-type structure. The substitution of Mn for Co in Y2Co17−xMnx compounds leads to a monotonic increase in unit cell volume. The saturation magnetization remains nearly constant for x⩽3, then decreases quickly with increasing Mn content; this can be explained by the change of the 3d energy band structure and an electron transfer process. The Curie temperature TC is found to decrease rapidly with increasing Mn concentrations. X-ray diffraction measurement on magnetically aligned Y2Co17−xMnx compounds exhibit an easy-plane type of magnetic anisotropy at room temperature for x=0 and an easy-axis type of magnetic anisotropy at room temperature with x=1–7. Substitution of Mn for Co leads to a change of the magnetocrystalline anisotropy of the...
13 citations
TL;DR: In this paper, the effects of Mn substitution for Co on the structure and magnetic properties of Tb2Co17−xMnx compounds with x=0-7 were investigated.
Abstract: X-ray diffraction (XRD) and magnetization measurements were employed to investigate the effects of Mn substitution for Co on the structure and magnetic properties of Tb2Co17−xMnx compounds with x=0–7. XRD patterns show that all samples are single phase except the samples with x=6 and 7 which contain a small amount of impurity. The substitution of Mn for Co leads to a monotonic increase in unit cell volume. The saturation magnetization at 5 K remains nearly unchanged upon Mn substitution, while the Curie temperature decreases monotonically. XRD measurements on magnetically aligned powders with x=0–7 exhibit an easy-plane type of magnetic anisotropy at room temperature. For x=2, 3, and 4, spin reorientation transitions above room temperature are observed in the M–T curves. The magnetic phase diagram is given.
10 citations
TL;DR: In this paper, the magnetic properties of Tb2Co17-xAlx compounds with 0 less than or equal to x less than and equal to 4 were studied by means of magnetic measurements.
Abstract: The magnetic properties of Tb2Co17-xAlx compounds with 0 less than or equal to x less than or equal to 4 were studied by means of magnetic measurements. There is a strong decrease of the saturation moment and the Curie temperature with AI concentration. In a previous investigation, it was shown that increasing AI concentration in R(2)Co(17-x)AI(x) compounds leads to a sign reversal of the magnetocrystalline Co-sublattice anisotropy from easy-plane anisotropy for low AI concentration to easy-axis anisotropy for higher AI concentration. In the Tb(2)Co(17-x)AI(x) compounds, the competition between the planar Tb-and easy-axis Co-sublattice anisotropy does not lead to spin-reorientation transitions because the Tb-sublattice anisotropy dominates at all temperatures. The occurrence of spin reorientations in R(2)Co(17-x)AI(x) compounds is discussed in terms of a simple model description.
10 citations
TL;DR: In this article, the effect of Mn substitution for Co on the structure and magnetic properties of Ce2 Co17-x Mnx compounds with x = 0, 1, 2, 3, 4.
Abstract: X-ray diffraction (XRD) and magnetization measurements were employed to investigate the effect of Mn substitution for Co on the structure and magnetic properties of Ce2 Co17-x Mnx compounds with x = 0, 1, 2, 3, 4. XRD patterns show that all samples are single phase with the hexagonal Th2 Ni17 -type structure. The substitution of Mn for Co in Ce2 Co17-x Mnx compounds leads to a monotonic increase in unit-cell volume. The saturation magnetization at 5 K and the Curie temperature TC decrease monotonically with increasing Mn content. X-ray diffraction measurements on magnetically aligned Ce2 Co17-x Mnx powders with x = 0-4 exhibit an easy-axis type of magnetic anisotropy at room temperature. The substitution of Mn for Co leads to a change of the magnetocrystalline anisotropy of the Co sublattice from the basal plane to c -axis and strongly increases the uniaxial anisotropy of Ce2 Co17-x Mnx compounds. The magnetocrystalline anisotropy field HA is found first to increase and then decrease with increasing Mn concentration, attaining a maximum value of 30.1 kOe at x = 2.
9 citations
TL;DR: In this article, an investigation of the structure and the magnetic anisotropy of R2Co15Al2 (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) compounds has been performed by means of x-ray diffraction and magnetization measurements.
Abstract: An investigation of the structure and the magnetic anisotropy of R2Co15Al2 (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) compounds has been performed by means of x-ray diffraction and magnetization measurements. X-ray diffraction shows the prepared compounds to be single phase, having the hexagonal Th2Ni17-type structure for R=Y, Ho, Er, and Tm and the rhombohedral Th2Zn17-type structure for R=Ce, Pr, Nd, Gd, Tb, and Dy. Except for the Ce compound, the unit-cell volumes of R2Co15Al2 compounds decrease in accordance with the lanthanide contraction. Substitution of Al for Co in R2Co17 leads to a decrease of the saturation magnetization at 1.5 K and Curie temperature. The exchange-coupling constants JCo–Co and JR–Co have been calculated by using the method based on magnetic ordering temperature. It is found that the JR–Co has a small dependence on the R elements and is almost not affected by the Al substitution. The Ce compound is found to exhibit an anomalous lattice parameter and magnetic characteristi...
8 citations
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TL;DR: In this paper, the spin-orbit contribution to the magnetic anisotropy of Co atoms at individual Co sites in $R{\mathrm{Co}}_{5}$ compounds was evaluated.
Abstract: NMR results are used to evaluate the spin-orbit contribution to the magnetic anisotropy of Co atoms at individual Co sites in $R{\mathrm{Co}}_{5}$ compounds. The easy $c$-axis Co anisotropy of $R{\mathrm{Co}}_{5}$ compounds is found to arise from the ($2c$) sites, while the ($3g$) sites make a smaller opposing contribution. The anisotropy parameters of the individual sites are used to calculate the variation of anisotropy with composition in mixed $R{({\mathrm{Co}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x})}_{5}$ compounds and also to estimate anisotropy parameters at individual sites in some structures related to the $R{\mathrm{Co}}_{5}$ phase.
166 citations
TL;DR: In this article, the substitution of Ga is found to play an important role in the stability of high carbon rare-earth iron compounds with 2:17-type structure, and a novel hard magnetic compound series with composition Sm2Fe14Ga3Cx (x=0, 0.5, 1.0, 1 5, 2.5) was prepared by arc melting.
Abstract: A novel hard magnetic compound series with composition Sm2Fe14Ga3Cx (x=0, 0.5, 1.0, 1.5, 2.0, and 2.5) was prepared by arc melting. The carbides crystallize in the rhombohedral Th2Zn17‐type structure and are single phase except for Sm2Fe14Ga3 and Sm2Fe14Ga3C0.5 which contain some amounts of α‐Fe. The substitution of Ga is found to play an important role in the stability of high carbon rare‐earth iron compounds with 2:17‐type structure. The Curie temperatures of Sm2Fe14Ga3Cx are 200–240 K higher than that of Sm2Fe17. All compounds with x=0–2.5 exhibit an easy c‐axis anisotropy at room temperature. The anisotropy fields increase with increasing carbon concentration from 70 kOe for x=0 to at least 90 kOe for x≥1.5. A room‐temperature coercivity of 15 kOe is obtained in Sm2Fe14Ga3C1.5 prepared by melt spinning at a speed of 30 m/s.
135 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.
125 citations
TL;DR: In this article, a new experimental technique is presented to determine the intersublattice molecular-field coefficient, n RT, in heavy rare earth-transition-metal intermetallic compounds.
100 citations