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Pseudobinary RCo7-xMx intermetallic compounds with TbCu7-type structure have been synthesized, and their structural and magnetic properties have been investigated using powder x-ray diffraction and magnetic measurements. Based upon the structural analysis, the stabilized element M occupies the 2e or the 3g position depending on its electronegativity. RCo7-xMx compounds exhibit ferromagnetic order with high Curie temperature. In addition, the uniaxial magnetocrystalline anisotropy is observed in SmCo7-xMx intermetallics. The magnetic moments have been investigated using a modified magnetic valence model with the equation =±xRZmR+xTZmT+2Nsp↑∑ixi, where the magnetic moment contributed by 4f transition metal is corrected from its chemical valence numbers of rare earth in the original magnetic valence model to the theoretical value of gJμBJ. It is also assumed that the nonmagnetic metal has no contribution to the moment. The corrected model can also be used to calculate the moments of the other strong ferromagnetic intermetallics such as R–(T,M) 1:5, 2:17, and R2Fe14B, etc. This model could estimate and even predict the moments as long as the composition of the ferromagnetic alloy is known. [ABSTRACT FROM AUTHOR]

Studies the effects of substitution of silicon for cobalt on the crystal structural stability and magnetic properties of NdCo[sub11-x]Si[subx] compounds. Experimental procedures; Results and discussion; Conclusion.

The effects of rare-earth contents, substitutions, and heat treatment parameters on the impact resistance of the Nd–Fe–B sintered magnets were investigated. Analysis shows that the impact resistance increases linearly with increasing plastic rare-earth-rich phase in the investigated magnets. Heavy rare-earth Dy substitutions for Nd help us to improve the impact resistance. The bending strength and impact resistance during annealing process was investigated. It is found that the annealing process affects the bending strength and impact resistance remarkably. Both the bending strength and the intrinsic coercivity are poor in the as-sintered specimen. In the postsintering annealing process, both of them get improved and the change of intrinsic coercivity is similar to that of the bending strength. Study showed that the optimized heat treatment parameters help us to improve the bending strength and impact resistance of the sintered Nd–Fe–B magnets. Study shows that the sintered Nd–Fe–B magnets with improved impact resistance can be produced by the adjustment of compositions and heat treatment parameters. [ABSTRACT FROM AUTHOR]

The crystal structure and magnetic properties of EuMnxGa3-x intermetallics have been investigated using powder x-ray diffraction and magnetic measurement. EuMnxGa3-x crystallizes in an orthorhombic structure with a space group of Cmcm, and Z=4. The lattice parameters are a=4.294(1)–4.287(1) Å, b=18.50(3)–18.57(3) Å, and c=4.384(6)–4.372(9) Å. In each unit cell, there are four nonequivalent 4c crystal positions for 4Eu, 4GaI, 4(GaII,Mn), and 4GaIII. EuMnxGa3-x (x<0.27) intermetallic compounds are antiferromagnetic at low temperature. A magnetic transition from the paramagnetic to the ferromagnetic occurs in EuMn0.3Ga2.7 at room temperature when applying a low field of 40 Oe. Moreover, this ferromagnetic order is very weak and sensitive to the applied field. With increasing the applied field, the ferromagnetic order tends to vanish. This phenomenon might be interpreted as the Mn spin state change induced by charge balance at low field. [ABSTRACT FROM AUTHOR]

The crystal structure and magnetic properties of EuMnxGa3-x intermetallics have been investigated using powder x-ray diffraction and magnetic measurement. EuMnxGa3-x crystallizes in an orthorhombic structure with a space group of Cmcm, and Z=4. The lattice parameters are a=4.294(1)–4.287(1) Å, b=18.50(3)–18.57(3) Å, and c=4.384(6)–4.372(9) Å. In each unit cell, there are four nonequivalent 4c crystal positions for 4Eu, 4GaI, 4(GaII,Mn), and 4GaIII. EuMnxGa3-x (x<0.27) intermetallic compounds are antiferromagnetic at low temperature. A magnetic transition from the paramagnetic to the ferromagnetic occurs in EuMn0.3Ga2.7 at room temperature when applying a low field of 40 Oe. Moreover, this ferromagnetic order is very weak and sensitive to the applied field. With increasing the applied field, the ferromagnetic order tends to vanish. This phenomenon might be interpreted as the Mn spin state change induced by charge balance at low field. [ABSTRACT FROM AUTHOR]

Polycrystalline La[SUB0.96-x]Nd[SUB-x]K[SUB0.04]MnO[SUB3] has been studied by means of x-ray powder diffraction, dc magnetization, and electrical resistance measurement. La[SUB0.96-x]Nd[SUBx]K[SUB0.04]MnO[SUB3] initially crystallizes in a rhombohedral distorted perovskite structure. However, an orthorhombic structure is obtained with increasing Nd content more than 20%. Both the rhombohedral and the orthorhombic phases show ferromagnetic order. However, the compound shows a magnetic inhomogeneity behavior with increasing Nd content. With increasing Nd doping, the ferromagnetic order is significantly weakened, and the second magnetic transition occurs at a low temperature and its peak intensity enhances. The resistivity of these compounds also exhibits an imhomogeneity behavior. The rhombohedral phase shows a metal-insulator (MI) transition but the MI transition peak intensity is obviously weakened and broadens with increasing Nd content and a low temperature insulator state is observed in the orthorhombic phase. It is interesting that the second magnetoresistance ratio peak appears at low temperature. It might be due to Nd induced low temperature phase separation between the ferromagnetic metallic and antiferromagnetic insulating state. [ABSTRACT FROM AUTHOR]

The polycrystalline Yb[sub χ]Ca[sub 1-χ]MnO[sub 3] (χ = 0.1,0.2) were studied by x-ray powder diffraction, magnetic, and electrical resistivity measurements. The Yb[sub χ]Ca[sub 1-χ]MnO[sub 3] crystallizes in an orthogonally distorted perovskite structure, and shows the ferromagnetic ordering with T[sub C] more than 110 K. However, the field dependence of magnetization and electrical resistivity exhibits very complicated behavior. A magnetic field induced insulator-metal transition has been found in the Yb[sub 0.2]Ca[sub 0.8]MnO[sub 3] compound. In addition, the large asymmetry in magnetization and resistivity hysteresis loops has been observed in this compound at 10 K, which might be due to the charge ordering and magnetocrystalline anisotropy. [ABSTRACT FROM AUTHOR]

The crystal structures and magnetic properties of RFe[sub 6-χ]Ga[sub 6 + χ] (R = Ce, Pr, Nd, Sm, and Gd) alloys have been investigated by x-ray powder diffraction and magnetic measurement. A ternary intermetallic compound with an orthorhombic ScFe[sub 6]Ga[sub 6] type structure is found in these alloys. The lattice parameter contraction is observed when the higher atomic number lanthanides are substituted into the intermetallic. In each unit cell, there are six nonequivalent crystal positions, i.e., 2a, 4e, 4f, 4g, 4h, and 8k, which are occupied by 2R, 4Ga[sup I], 4(Fe[sup I],Ga), 4Ga[sup II], 4Ga[sup III], and 8Fe[sup II], respectively. The RFe[sub 6-χ]Ga[sub 6 + χ] alloys have ferromagnetic ordering but the magnetic transitions have been found in Nd based alloy. The RFe[sub 6-χ]Ga[sub 6 + χ] alloys show a soft magnetic behavior but the magnetization hysteresis loops have been observed in the Nd and Sm alloys at 5 K. The saturated magnetic moments per molecule tend to increase from Ce to Nd. However, a drastic decrease of magnetic moment in GdFe[sub 6]Ga[sub 6] alloy is observed and is likely due to the Gd spin alignment being antiparallel to Fe spin. The saturation magnetic moments of these alloys are calculated and agree with the experimental values. [ABSTRACT FROM AUTHOR]

Features a study that examined iron-based rare-earth cerium (Ce)-iron (Fe)-silicon (Si) intermetallic compounds. Measurement of alternate current susceptibility and magnetization curves of the compounds; Discussion on magnet materials; Information on the x-ray-diffraction pattern of a CeFeSi compound.

The crystal structure and the magnetic and electronic transport properties of Ge doped LaCo10.5Si2.5-xGex (x=0–0.3) intermetallics have been investigated using powder x-ray diffraction and magnetic and electrical measurements. According to the x-ray diffraction pattern analysis, Ge as a dopant decreases the stability of the cubic LaCo 1:13 phase and stabilizes the Si based La(Co,Si) 1:13 tetragonal phase. From the authors’ structural refinement, the authors found that Ge prefers to occupy the 16l(2) position in the tetragonal phase. LaCo10.5Si2.2Ge0.3 shows ferromagnetic order with a metamagnetic state around 350 K. An anomaly in resistivity is observed at around 367 K, which is associated with the metamagnetic transition. The resistivity follows ρ(T)=ρo+aTn rule in the temperature range of 4–400 K with n=1.17(3) for the half metallic state and n=2 for the normal metallic state, respectively. This type of discontinuity can be interpreted as a crossover from a low temperature metamagnetic half metallic state to the normal ferromagnetic-metallic state. [ABSTRACT FROM AUTHOR]