Effects of Co substitution on structural and magnetic properties of R< sub> 3(Fe< sub> 1− x Co< sub> x)< sub> 29− y V< sub> y(R= Tb, Dy) (original) (raw)
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Effects of Co substitution on structural and magnetic properties of R3(Fe1−xCox)29−yVy (R=Tb, Dy)
Journal of Magnetism and Magnetic Materials, 2002
Synthesis of two novel series of intermetallic compounds Tb3 (Fe1− xCox) 27.4 V1. 6 (x= 0, 0.1, 0.2, 0.3, 0.4) and Dy3 (Fe1− xCox) 27.8 V1. 2 (x= 0, 0.1, 0.2, 0.3) with the monoclinic Nd3 (Fe, Ti) 29-type structure (3: 29) is presented. In the Dy series for x= 0.4 a disordered variant of the hexagonal Th2Ni17-type structure is formed. The cell parameters decrease and the Curie temperature increases with increasing of the Co content. In the case of the Tb3 (Fe1− xCox) 27.4 V1. 6 series in the M (T) curve a magnetic transition is observed ...
Journal of Alloys and Compounds, 2006
The study of the effect of Co substitution on the structural and magnetic properties of R 3 (Fe 1−x Co x) 29−y M y (R = Y, Nd, Tb, Dy; M = Ti, V, Cr, Mn; 0 ≤ x ≤ 1; y = 0.9-7.0) is presented. For the compounds with low Co content (0 ≤ x ≤ 0.4) the unit cell volume is decreasing as the Co content increases. 57 Fe Mössbauer spectroscopy has shown that the Co atoms avoid the dumb-bell sites. The Curie temperature values, T C , increase monotonically with x. For the compounds with high Co and low M content (0.6 ≤ x ≤ 1 and y = 1.6) the situation is rather different. Starting with the 3:29 stoichiometry a disordered variant of the hexagonal Th 2 Ni 17-type structure is formed. In Y 3 (Fe 1−x Co x) 29−y Cr y the monoclinic 3:29 structure is retained if the amount of the stabilizing element is increased. The T C values of the compounds are reduced; this should be attributed to the larger Cr content. The same behavior is observed in the case of Nd based products with 0.6 ≤ x ≤ 1 stabilized by Cr or Mn.
J. Alloys Compd. 367(1-2) pp. 255-261 (2004)
Starting with the Nd3(Fe,Ti)29 stoichiometry [Tb3(Fe1-xCox)27.4V1.6 and Dy3(Fe1-xCox)27.8V1.2; x= 0.6, 0.8, 1.0] two novel series of R-Fe-Co-V intermetallic compounds with a disordered variant of the hexagonal Th2Ni17-type structure were formed. The cell parameters decrease and the Curie temperature increases with increasing Co content. XRD patterns of magnetically aligned powder samples revealed the presence of planar magnetic anisotropy. Keywords: R-TM intermetallics (A); Magnetically ordered materials (A); Powder metallurgy (B); X-ray and γ-ray spectroscopy (D); Magnetic measurements (D)
Structure and magnetic properties of (Nd,Y)3(Fe,Co,Ti)29 compounds
Physica B: Condensed Matter
A series of Co-substituted compounds with nominal stoichiometries Nd 1Àx Y x Fe 27.7Ày Co y Ti 1.3 (x ¼ 0.3-2.1, y ¼ 3,6) and Nd 1.5 Y 1.5 Fe 27.7Ày Co y Ti 1.3 (y ¼ 3,6,9,11) were prepared and their structures were analyzed with powder X-ray diffraction (XRD) and neutron diffraction (ND). All samples are found to crystallize mainly in the R 3 (Fe,Ti) 29-type structure with monoclinic symmetry (space group A2/m). The lattice parameters a, b and c and the unit cell volume V decrease monotonically with the increase of Y or Co content. The Curie temperature T c and the saturation magnetization M s are both found to increase with increasing Co content. The results of Rietveld refinements of the neutron diffraction data show that the stabilizing Ti atoms are distributed over the Fe2, Fe3 and Fe6 sites, while the Co atoms mainly occupy those Fe sites not shared with Ti atoms, particularly Fe8 and Fe11 sites.
Structural and magnetic properties of Nd3(Fe1−xCox)27.7Ti1.3 (0
Journal of Alloys and Compounds, 2001
Structural and magnetic properties of a novel series of intermetallic compounds, with nominal stoichiometry Nd (Fe Co) Ti 3 1 2x x 27.7 1.3 (0,x#0.4) are presented. The samples crystallise in the Nd (Fe,Ti)-type structure with monoclinic symmetry (space group A2 /m). The 3 2 9 unit cell volume is decreasing as the Co content increases; the cell parameters show anisotropic decrease with the Co content. The Curie temperature increases monotonically with x from 437 to 878 K and the room temperature saturation magnetisation increases from 143.3 2 for x50 to 172.5 Am / kg for x50.3 and remains practically the same for x50.4. For x50 and 0.1 a tilted magnetic structure is observed. For x$0.2 the compounds present an easy-magnetisation direction along the [4 0 22] direction. Ac susceptibility curves in the whole range of the Co content (x50-0.4) reveal a broad transition at about 160 K, whereas for x50-0.2 a sharp one with the corresponding transition temperature decreasing with increasing Co content. The observed changes of the critical temperatures observed in the ac susceptibility curves and the obtained anisotropy field values are related to the change of the magnetic anisotropy at x50.2. The average hyperfine field values depend on the Co content in a way similar to the dependence of the saturation magnetisation.
Journal of Alloys and Compounds, 2007
The structural and magnetic properties of compounds with nominal composition Y 3 (Fe 1−x Co x) 29−y Cr y (x = 0.6-1.0 and y = 5-7) have been investigated. The main phase formed was that of Nd 3 (Fe,Ti) 29-type structure (3:29) with a significant amount of a disordered variant of the hexagonal Th 2 Ni 17-type structure (2:17H) as a secondary phase (25-50 wt.%), especially for higher Co (80% and above) content. The unit cell volume is decreasing with the increase of the Co and Cr content, as well as all the cell parameters. The Curie temperature of both phases decreases monotonically with x and y. The x = 1.0 compound is paramagnetic at room temperature. The x = 0.6, 0.8 compounds present uniaxial anisotropy along the [2 0 4] direction of the monoclinic Nd 3 (Fe,Ti) 29-type structure, which should be attributed to the transition metal sublattice. The saturation magnetization and the anisotropy field are lower in the sample with x = 0.8 compared to the one with x = 0.6. This reduction is also observed in the Mössbauer spectra of the materials at room temperature which are also presented.
Crystal structure and magnetic properties of Nd 1− x Y x Co 6.86Hf 0.14 compounds
Fuel and Energy Abstracts, 2005
The Nd1−xYxCo6.86Hf0.14 compounds with x=0–0.4 have been investigated by means of X-ray powder diffraction and magnetic measurements. The as-cast Nd1−xYx(Co,Hf)7 compounds crystallize in the hexagonal TbCu7-type structure with the space group P6/mmm. The lattice parameter a and the cell volume V decrease linearly with the Y content while c holds almost constant. The saturation moment per formula unit decreases linearly with the Y content, but the saturation moment per Co atom increases with the Y content. The Curie temperature and the magnetic anisotropy field of the compounds increase with the Y content. The increase of the Curie temperature is mainly related to the increase of the Co–Co exchange interaction due to the volume reduction effect. The Nd1−xYx(Co,Hf)7 compounds with x=0–0.4 show basal plane anisotropy at 5 K. The room temperature easy magnetization direction of the Nd1−xYx(Co,Hf)7 compounds changes from basal plane to c-axis with increase in the Y content. The spin reorientation (SR) transition has been found in the Nd1−xYx(Co,Hf)7 compounds and the SR temperature decreases with the Y content.