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The magnetic structure of Nd6Fe13Si

The magnetic structure of Nd6Fe13 Si has been studied by magnetization measurement, the singular point detection technique and neutron powder diffraction. It was found that the Nd6Fe13Si is ferrimagnetic with a compensation temperature of 357 K and a Curie temperature of 441 K. The spontaneous magnetization values are 12.9 J T-1 kg-1 at 5 K and 7.4 J T-1 kg-1 at 300 K. There are two values B0cr1 and B0cr2 of the magnetic phase transition field below 225 K: B0cr1=6.2 T and B0cr2=8.2 T at 77 K and B0cr=5.3 T at 300 K. The atomic magnetic moments are ordered in an antiparallel manner, and the two magnetosublattices are MI up arrow (8f(Nd), 16l(Nd), 4d(Fe), 16l2(Fe)) and Mn down arrow (16k(Fe), 161(Fe)).

Magnetic properties of new ternary R sub 6 Ga sub 3 Fe sub 11 compounds

Three new rare earth–iron ternary compounds with the La6Ga3Co11 structure (I4/mcm), Pr6Ga3Fe11, Nd6Ga3Fe11, and Sm6Ga3Fe11, are found to be ferromagnetic with Curie temperatures of 320, 397, and 462 K, respectively. Large anisotropies have been observed from the magnetization curves and the anisotropy field is larger than 7 T at room temperature. First‐order magnetization processes were observed for all samples throughout the temperature range of 4.2–300 K. Point charge calculations give A20=1070 K a−20 at the 16l site and −283 K a−20 at the 8f site.

Crystallographic and magnetic properties of Nd1+xFe10Mo2Ny

Abstract Nd 1+ x Fe 10 Mo 2 N y nitrides with permanent magnetic properties were prepared by heating fine Nd Fe Mo particles in an N 2 atmosphere followed by milling. The best composition and nitriding and milling conditions to obtain a high coercivity and energy product for the nitrides were investigated. H c and B r of magnetically aligned samples increased and decreased monotonically respectively with increasing milling time after nitriding irrespective of composition and nitriding conditions. The room temperature properties μ o H c = 0.7 T, B r = 0.4 T and ( BH ) max = 42 kJ m −3 were obtained.

Microstructure and magnetic properties of two-phase nanocomposite Nd9Fe85.5Nb1.0B4.5−yCy (y=0.5–4.5) magnets

Nanocrystalline two-phase Nd9Fe85.5Nb1.0B4.5-yCy magnets (y=0.5-4.5) have been prepared by melt spinning and subsequent heal treatment. The effect of remanence enhancement has been observed in the melt-spun ribbons after a proper annealing procedure. A two-phase nanocomposite Nd9Fe85.5Nb1.0B4.0C0.5 magnet with optimum magnetic properties of H-cj.=6.6 kOe, J(r)=10.22 kGs and (BH)(max)=13.32 MGOe has been obtained

MAGNETIC PHASE-DIAGRAM OF ND(FE,MO)12 ALLOYS

The magnetic phase diagram of the alloy series NdFe12−xMox (x=1.0∼2.5) is obtained. Below the Curie temperature, the ferromagnetic phase is divided into three regions: Uniaxial, canted 1, and canted 2. At a temperature of Tsr1 (below 200 K) a spin reorientation transition (SRT) was observed for all the samples, and at Tsr2 (above 200 K) another SRT was found for samples with Mo concentration 1.5<x<1.75. At room temperature the easy direction of magnetization (EDM) of NdFe12−xMox changes from the c axis to a canted structure with increasing Mo concentration, with a critical composition of x=1.56. At low temperatures (below 100 K) all NdFe12−xMox compounds exhibit a canted moment structure.

The magnetic phase diagram of DyFe12-xMox (1.00 <= x <= 3.00)

The magnetocrystalline anisotropy and magnetic structure of DyFe12−xMox (1.00≤x≤3.00) have been investigated in detail by X-ray diffraction, thermomagnetic analysis, AC magnetic susceptibility, singular point detection technique and angular-magnetization measurement. A magnetic phase diagram of DyFe12−xMox (1.00≤x≤3.00) has been proposed. At room temperature, all DyFe12−xMox compounds exhibit uniaxial anisotropy. At low temperature, a spin reorientation transition of axis-to-cone was observed for DyFe12−xMox compounds with low Mo concentration, x<2.00. The spin reorientation temperature decreases with increasing Mo concentration. For DyFe12−xMox compounds with high Mo concentration, magnetohistory effects were observed below 48 K.

Effects of volume expansion and electron correlation in some R(Fe,M)12 compounds (M=Nb, Ti, V) and their nitrides

Abstract In the present paper, a study of the effect of the volume change on the Curie temperature ( T C ) of R(Fe,M) 12 (M=Nb, Ti and V) due to nitrogenation has been performed. The dln T C /dln V values were derived by comparing the Curie temperatures and volumes before and after nitrogen. Our results indicate that the relationship between dln T C /dln V and the Curie temperature T C agrees with an itinerant-model formalism. The effects of volume expansion and the increasing electron correlation play important roles in the enhancement of the Curie temperature upon nitrogenation of intermetallic compounds.

Novel permanent magnetic material: Sm3(Fe,Ti)29Ny

Abstract The X-ray diffraction pattern of the novel Sm 3 (Fe 0.933 Ti 0.067 ) 29 compound was indexed on the basis of monoclinic symmetry with the lattice parameters a = 1.065 nm, b = 0.858 nm, c = 0.972 nm and β = 96.98°. The Sm 3 (Fe 0.933 Ti 0.067 ) 29 compound exhibits ferromagnetic ordering with T C = 486 K and a planar anisotropy. The new interstitial nitride of the Sm 3 (Fe 0.933 Ti 0.067 ) 29 N 5 compound was obtained by gas-solid phase reaction. The nitride has the same structure as the parent compound. The introduction of nitrogen leads to an increase in the Curie temperature to 750 K. The saturation magnetization values σ s = 160 A m 2 kg −1 at 4.2 K and 140 A m 2 kg −1 at 293 K. The anisotropy was changed from planar to uniaxial upon nitrogenation. The anisotropy field B a values were 18.1 T at 4.2 K and 12.8 T at 293 K. The hard magnetic properties of the Sm 3 (Fe 0.933 Ti 0.066 ) 29 N 5 compound have been studied. A coercivity μ 0i H c value of 0.83 T and a maximum energy product ( BH ) max of 105 kJ m −3 at 293 K have been achieved. The Sm 3 (Fe 0.933 Ti 0.067 ) 29 Ny compound is a promising material for permanent magnetic applications.

Crystallographic and magnetic properties of a Tb3(Fe,Cr)29 single crystal

A Tb-3(Fe,Cr)(29) single crystal with the monoclinic Nd-3(Fe,Ti)(29)-type structure was obtained after proper heat treatment on the original single crystal with a hexagonal structure grown by the Czochralski method. The magnetization curves along the hard and easy directions are presented. The lattice parameters are a = 1.058 nm, b = 0.848 nm, c = 0.968 nm, alpha = gamma = 90 degrees, and beta = 96.93 degrees, respectively. The Curie temperature is 477 K and the saturation magnetizations are 51.74 A m(2)/kg (18.07 mu(B)/f.u.) at 1.5 K and 58.34 A m(2)/kg (20.38 mu(B)/f.u.) at 293 K, respectively. Below room temperature, a first-order magnetization process of type II occurring at the critical field of 6.0 T at 100 K and 5.5 T at 200 K was observed. A magnetohistory effect taking place at about 175 K was also detected on the Tb-3(Fe,Cr)(29) single crystal

Hard magnetic properties of Sm3Fe26.7VxN4 and Sm3Fe26.7VxCy

Sm3Fe26.7V2.3N4 nitrides and Sm3Fe26.7V2.3Cy carbides have been synthesized by gas-solid phase reaction. Their hard magnetic properties have been investigated by means of additional ball-milling at room temperature. The saturation magnetization of Sm3Fe26.7V2.3N4 almost decreases linearly with increasing ball-milling time t, but that of Sm3Fe26.7V2.3Cy has no obvious change when the ball-milling time increases from t = 1 to 28 h. As a preliminary result, the maximum remanence B-r of 0.94 and 0.88 T, the coercivity mu(0i)H(C) of 0.75 and 0.25 T, and the maximum energy product (BH) of 108.5 and 39.1 kJ/m(3) for their resin-bonded permanent magnets are achieved, respectively, by ball-milling at 293 K