Yang Fu-ming

ROOM-TEMPERATURE MAGNETIC-ANISOTROPY OF RARE-EARTH TRANSITION-METAL INTERMETALLICS R2FE14C (R = LU, GD, ND) AND R2FE14B (R = GD, ND)

Magnetic anisotropy fields at room temperature of ternary tetragonal compounds of R2Fe14C(R = Lu, Gd, Nd) and R2Fe14B(R = Gd, Nd) were determined by Singular-Point-Detection (SPD) technique. The magnetocrystalline anisotropies of the carbides were found to be larger than those of their corresponding borides, indicating that the outstanding permanent-magnetic properties may be obtained in the R2Fe14C-based alloys.

Formation and magnetic properties of Sm3(Fe,Ti)29Ny compounds

The formation and magnetic properties of a novel intermetallic Sm3(Fe0.933Ti0.067)29 compound and the Sm3(Fe0.933Ti0.067)29Ny (y=5) nitride have been investigated. The x-ray diffraction patterns of the nitride and the parent compound were indexed on the basis of the Nd3(Fe,Ti)29-type structure with monoclinic symmetry. The parent and the nitride exhibit ferromagnetic ordering with a Curie temperature TC of 486 K for the parent and 750 K for the nitride. Introduction of nitrogen led to an increase in saturation magnetization; Ms for the nitride is 160 A m2 kg-1 at 4.2 K and 140 A m2 kg-1 at 293 K. The nitride has a uniaxial anisotropy with an anisotropy field strength Ba for 25 T at 4.2 K and 12.8 T at 293 K. The coercivity mu 0iHc=0.83 T at 293 K for this new nitride has been determined.

New intermetallic compounds RCo9Si4 (R=Pr, Nd) with a tetragonal NaZn13-derivative structure

Abstract Two new intermetallic compounds RCo 9 Si 4 (R = Pr, Nd) with tetragonal NaZn 13 -derivative structure have been synthesized. Their crystal structures have been determined by X-ray powder diffraction and refined by the Rietveld technique. The space group for the tetragonal structure is I 4/ mcm . The lattice parameters are a = 7.789(1) A , c = 11.509(2) A and a = 7.791(2) A , c = 11.516(3) A for PrCo 9 Si 4 and NdCo 9 Si 4 respectively. The Si atoms strongly prefer to occupy the crystallographic 161(2) position.

Magnetic properties of Sm2Fe17Ny with Al substituted for Fe

By means of X-ray diffraction analysis, it is shown for x < 0.4 that all the interstitial Sm-2(Fe1-xAlx)(17)N-y nitrides and the parent compounds crystallize with Th2Zn(17)-type structure. The lattice constants of the parent compounds increase linearly with Al concentration. The introduction of nitrogen atoms leads to a further increase in the lattice constants, but the increase becomes smaller with increasing Al concentration; this can be related to the fact that the nitrogen content introduced into the parent compounds decreases nearly linearly with increasing Al concentration. The dependence on composition of T-c of the parent compounds exhibits a maximum, whereas T-c of the nitrides decreases monotonically with Al content from 750 K for x=0 to 313 K for x=0.4. The introduction of nitrogen leads to enhancement of the average magnetic moment of Fe in Sm2Fe17, whereas the substitution of Al for Fe leads to a decrease in the average magnetic moment of Fe in both the nitrides and the parent compounds. The anisotropy field B-a of nitrides is almost independent of the Al concentration for x less than or equal to 0.3, then decreases very fast and becomes zero at about x = 0.4.

Magnetic behaviour of heavy rare earth compounds of the type RFe10Cr2

Abstract Lattice constants, high field magnetic isotherms at 4.2 K 1 Curie temperatures and spin reorientation temperatures are reported for RFe 10 Cr 2 compounds with R ≈ Y, Gd, Tb, Dy, Ho, Er, Tm, Lu. The value of the rare earth-transition metal (T) magnetic coupling constant J RT / k derived by a mean field analysis of the Curie temperatures is about − 15 K. This value is larger than the value of about −9 K obtained in a mean field analysis of the effect of the departure of the perfect collinear ferrimagnetic orientation of the sublattice magnetizations occurring in high magnetic fields. A tentative spin phase diagram for the RFe 10 Cr 2 series is presented.

Magnetic anisotropy in Pr2Fe14−xMnxC compounds

Abstract The concentration dependence of the magnetic properties of Pr 2 Fe 14− x Mn x C, 0.3≤ x ≤10, compounds has been in Mn substitution leads to a decrease of the saturation moment, accompanied by a strong reduction of the Curie temperature. Anisotropy constants have been deduced from an analysis of high-field magnetisation isotherms at 4.2 K. First-order magnetisation processes (FOMP) have been observed.

Complex antiferromagnetic order of CeCuSn

Abstract CeCuSn, which forms in the hexagonal CaIn 2 -type of structure, orders antiferromagnetically at 8.6 K. A second maximum at about 7.35 K seen in the temperature dependence of the specific heat indicates a rearrangement of the antiferromagnetic structure. The antiferromagnetic ordering is also reflected in the temperature dependence of the electrical resistivity. Upon application of magnetic fields up to 5 T, a complex development of magnetic phases can be followed by monitoring the temperature dependencies of the magnetization and the specific heat. In the B-T diagram, three different magnetic phases were detected and their boundaries could be determined.

High-field magnetization of Pr2Fe14B-based compounds

Abstract Magnetic isotherms in fields up to 35T have been measured at 4.2 and 77K on magnetically-aligned powders of (Pr,R) 2 Fe 14 B compounds with R = Gd, Nd, Er and Sm. Anisotropy constants up to sixth order have been derived. The influence of the various rare-earth substitutions upon the first-order magnetization process in Pr 2 Fe 14 B has been studied.

STRUCTURE AND MAGNETIC PROPERTIES OF NDCO13-XSIX

NdCo13-xSix (2.5 less than or equal to x less than or equal to 4.0) compounds have been prepared by are melting and subsequent annealing. X-ray powder diffraction indicated that they crystallized in a tetragonal NaZn13-derivative structure. Thermomagnetic measurements in an applied held of 1.2 T revealed that the compounds are ferromagnetic. From the magnetization at 1.5 K a value of 2.2 mu(B) is obtained for the magnetic moment of Nd3+, and this value is about 1.4 mu(B) smaller than the value of a free Nd3+ ion, i.e., the Nd3+ moment in these compounds seems to be significantly quenched

Synthesis and Magnetic Properties of Gd3 (Fe, Co, Cr)29 Compounds

Formation and magnetic properties of the Gd3Fe29-x-yCoxCry compounds have been investigated. It has been found that formation of single-phase compounds Gd3Fe29-x-yCoxCry with the Nd3(Fe,Ti)29-type structure depends strongly on the content of the stabilizing element Cr, and the solid-solution limit of Co in Gd3Fe29-x-yCoxCry compounds increases with Cr content. Pure Co-based Gd3Co29-yCry compounds with the Nd3(Fe,Ti)29-type structure have been successfully synthesized with y = 6.5 and 7.0. The Curie temperature TC of Gd3Fe29-x-yCoxCry compounds increases with increasing Co content x at fixed y, whereas the increase of the Cr content leads to an obvious decrease of TC of the Gd3Co29-yCry compounds. Composition dependence of the saturation magnetization at 5 K reaches a maximum around x = 7.5 and y = 4. It is worth noting that substitution of Co for Fe results in a significant change of magnetocrystalline anisotropy of the Gd3Fe29-x-yCoxCry compounds and changes the easy magnetization direction from basal-plane to easy-axis when x>10 and y = 4.