Hs Li

Structural study of the rare-earth transition-metal intermetallic compound Nd3Ni29Si4B10

The novel quaternary rare-earth transition-metal intermetallic compound Nd3Ni29Si4B10 of space group P4/nmm (No. 129) has been synthesised and its structure determined. The crystal structure has been investigated by scanning electron microscopy, X-ray and neutron powder diffraction measurements. Rietveld refinements of the powder X-ray and neutron diffraction patterns reveal a tetragonal structure of lattice parameters a=b=11.2327(7) A, c=7.8754(3) A with two formula units of Nd3Ni29Si4B10 per unit cell. The structure contains two rare-earth crystallographic sites of high symmetry, four B sites, seven transition metal sites and one Si site. The Ni atoms at the 2c 4 mm crystallographic site have a quasi-spherical polyhedral coordination.

X-ray and magnetic single-crystal analysis of the crystallographic structure of the Y3(Fe0.933V0.067)29 compound

Abstract The formation of a sizeable single crystal of the Nd 3 (Fe,Ti) 29 -type phase, namely Y 3 (Fe 0.933 V 0.067 ) 29 is reported. It was prepared by the solid-state transformation of a Y 2 (Fe,V) 17 single crystal whose chemical composition is Y 3 (Fe,V) 29 . Initial disagreement between powder and single-crystal X-ray data has been resolved by performing magnetization measurements on single crystal. These measurements show a peculiar behaviour and have been quantitatively analysed by considering that the crystal is actually twinned. Refinement of the single-crystal data is then re-examined and confirms the monoclinic structure already reported for this system.

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.

Magnetic properties of single crystal Y3(Fe0.93V0.07)29

Abstract We have successfully prepared a Y 3 (Fe 0.93 V 0.07 ) 29 single crystal by the Czochralski method followed by an appropriate annealing procedure. The spontaneous magnetization lies in the (1 0 2)-plane over the investigated temperature range of 5–300 K. The Curie temperature is T c = 439 K. The saturation magnetization at 5 K is M s = 48.3 μ B /f.u. which corresponds to an average Fe magnetic moment of 1.79 μ B . The uniaxial anisotropy K 1 * of Fe-sublattice at T = 5 K is — 2.25 MJ/m 3 . We observed no easy magnetization direction within the (1 0 2)-plane which may be due to the coexistence of Y 3 (Fe,V) 29 crystallites, oriented to each other at a relative angle of θ = 60° about the [1 0 2] axis. This feature has been well explained with a six-domain model in terms of the anisotropy constants K i ( T ) of the iron sublattice of the monoclinic 3 : 29 structure.

Magnetic behaviour of Nd3Co29Si4B10

Abstract The magnetic behaviour of a novel quaternary rare-earth compound Nd 3 Co 29 Si 4 B 10 has been investigated by AC magnetic susceptibility and 57 Fe Mossbauer effect spectroscopy measurements. The Nd 3 Co 29 Si 4 B 10 compound exhibits a magnetic transition around T c1 ≈ 200 K with a second magnetic transition occurring around T c2 ≈ 43 K. Addition of ≈ 0.5 wt% 57 Fe is found to decrease the magnetic ordering temperatures to T c1 ≈ 167 K and T c2 ≈ 38 K. Similar to other Co-rich, light rare-earth compounds, Nd 3 Co 29 Si 4 B 10 is likely to exhibit ferromagnetic ordering below T c1 .

Spin reorientation in HoCo12B6

Mossbauer and AC susceptibility experiments on HoCo12B6 (57Fe) show that the Fe atoms exhibit a strong preferential occupation of the 18h site. HoCo12B6 undergoes an axis to plane spin reorientation at T sr = 75(2) K.