Lin‐shu Kong

Magnetocrystalline anisotropies of RTiFe11Nx compounds

We have discovered that the rare‐earth–iron intermetallics of the type RTiFe11 can absorb moderate quantities of nitrogen at 500 °C, giving the approximate composition RTiFe11N0.5 at 1 atm. X‐ray diffraction showed that the tetragonal structure (I4/mmm) is retained but that the unit cell volume is slightly increased. More significantly, profound change of magnetocrystalline anisotropy have occurred upon the absorption of nitrogen. In this letter, we report the lattice parameters and magnetocrystalline anisotropic properties of RTiFe11Nx compounds.

Magnetic and crystallographic properties of novel Fe‐rich rare‐earth nitrides of the type RTiFe11N1−δ (invited)

We succeed in inserting a number of nitrogen atoms into the RTiFe11 intermetallics. The nitrides retain the ThMn12‐type structure, but with an increase in the unit cell volume. The crystallographic sites located by nitrogen atoms are determined by using neutron diffraction techniques. The nitrogen atoms are found to have an effect of increasing Curie temperature and saturation magnetization. Moreover, an essential change in magnetocrystalline anisotropy is observed upon nitrogenation. By all of these effects, the NdTiFe11N1−δ compounds have excellent intrinsic magnetic properties favorable for permanent magnet applications.

New potential hard magnetic material-NdTiFe11Nx

Abstract The absorption of nitrogen in ternary compounds of the type RTiFe 11 has been studied, where R = Y , Nd , Sm . X-ray diffraction showed that the tetragonal structure ( I 4/ mmm ) is retained but that the unit cell volume is slightly increased. Furthermore, nitrogen absorption both increases the Curie temperature, and gives rise to a drastic changing of magnetocrystalline anisotropy in RTiFe 11 N x compounds. Among them, NdTiFe 11 N x now has high magnetization, high Curie temperature and easy axis magnetocrystalline anisotropy potentially suitable for permanent magnet applications.

NEUTRON DIFFRACTION STUDY OF THE NITRIDE YTIFE11NX

Abstract A neutron diffraction study was carried out on a powder sample of the composition YTiFe 11 N 0.5 at 300 K. Neutron diffraction measurements not only confirm that the nitride maintains the tetragonal structure of its virginal compound YTiFe 11 ( ThMn 12 - type , I 4/ mmm ), but also indicate that the nitrogen atoms occupy the interstitial 2b sites. A detailed analysis of the crystallographic and magnetic structure is presented, and the relationship of the magnetic properties to the crystallographic structure is discussed in this paper.

Neutron diffraction study of Y(Ti,Fe)12

Neutron diffraction experiments on Y(Ti,Fe)12 have been carried out to investigate the crystallographic structure and magnetic properties of these compounds. In the ThMn12‐type structure, with a space group of I4/mmm, Fe and Ti atoms are distributed on three nonequivalent crystallographic sites. A preferential site occupation for Fe and Ti is observed. The detailed analysis of crystallographic and magnetic arrangement are reported.

Neutron‐diffraction study of YTiCo11 and YTi(Co0.5Fe0.5)11

The compounds YTi(Fe1−xCox)11 form complete solid solutions (0≤X≤1) all of which crystallize in the ThMn12‐type tetragonal structure. The substitution effects of Fe with Co on saturation magnetization and Curie temperature have been investigated. A neutron‐diffraction study has been carried out on YTiCo11 and YTi(Co0.5Fe0.5)11. A strong preferential site occupation for Co and Ti atoms is observed. A detailed analysis of crystallographic and magnetic arrangement is presented.

Theoretical explanations of magnetocrystalline anisotropy behaviors in RTiFe11Nx compounds

The RTiFe11Nx compounds have higher Curie temperatures, larger saturation magnetization, and entirely different magnetocrystalline anisotropy behavior as compared with the RTiFe11 compounds. In contrast to RTiFe11, the c axis becomes the easy magnetization direction of RTiFe11Nx when R=Nd, Tb, Dy, and Ho, while SmTiFe11Nx has an easy plane and ErTiFe11Nx presents a spin reorientation at about 45 K. Theoretical calculations were made to explain those anisotropy behaviors. The calculation results show that the changes in anisotropy behaviors could be attributed to the large positive contribution of nitrogen atoms located at 2b interstitial sites to the second‐order crystal‐field coefficient A20.

Neutron diffraction study of ternary nitrides of the type R2Fe17Nx

We have carried out neutron diffraction measurements on powder samples of Nd2Fe17Nx and Y2Fe17Nx at room temperature. The refinements of the neutron data indicate that the nitrogen atoms occupy the 9e interstices in the nitride Nd2Fe17Nx (Th2Zn17 type, R3m) or the 6h interstices in the nitride Y2Fe17Nx (Th2Ni17 type, P63/mmc), respectively. At room temperature, both Nd2Fe17Nx and Y2Fe17Nx adopt a magnetic structure in which the easy magnetization direction is perpendicular to the c axis. Using the above results, we have briefly discussed the effect of a nitrogenation on the magnetocrystalline anisotropy of the Sm sublattice of Sm2Fe17Nx.

Magnetic properties of Sm2(Fe1−xCox)17C and Y2(Fe1−xCox)17C

The crystallographic structure and magnetic properties of Sm2(Fe1−xCox)17C with x equal to 0.0, 0.1, 0.2, 0.3, 0.4, 0.7, and 1.0, and Y2(Fe1−xCox)17C with x equal to 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 1.0 have been investigated. They crystallize in the rhombohedral Th2Zn17‐type structure or the hexagonal Th2Ni17‐type structure. The Curie temperatures increase with increasing cobalt content and the saturation magnetizations reach a maximum at x=0.3. All Sm2(Fe1−xCox)17C compounds have an easy axis, but the anisotropy fields have a dependence on cobalt content. Both Y2Fe17C and Y2Co17C have an easy plane. However, an easy axis is found in a concentration range with 0.4The crystallographic structure and magnetic properties of Sm{sub 2}(Fe{sub 1{minus}{ital x}}Co{sub {ital x}}){sub 17}C with {ital x} equal to 0.0, 0.1, 0.2, 0.3, 0.4, 0.7, and 1.0, and Y{sub 2}(Fe{sub 1{minus}{ital x}}Co{sub {ital x}}){sub 17}C with {ital x} equal to 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 1.0 have been investigated. They crystallize in the rhombohedral Th{sub 2}Zn{sub 17}-type structure or the hexagonal Th{sub 2}Ni{sub 17}-type structure. The Curie temperatures increase with increasing cobalt content and the saturation magnetizations reach a maximum at {ital x}=0.3. All Sm{sub 2}(Fe{sub 1{minus}{ital x}}Co{sub {ital x}}){sub 17}C compounds have an easy axis, but the anisotropy fields have a dependence on cobalt content. Both Y{sub 2}Fe{sub 17}C and Y{sub 2}Co{sub 17}C have an easy plane. However, an easy axis is found in a concentration range with 0.4{lt}{ital x}{lt}0.9 for the substituted Y{sub 2}(Fe{sub 1{minus}{ital x}}Co{sub {ital x}}){sub 17}C compounds.

Magnetocrystalline anisotropy of TbTiFe11N1−δ and DyTiFe11N1−δ

Abstract We have succeeded in introducing moderate quantities of nitrogen into TbTiFe 11 and DyTiFe 11 compounds. X-ray diffraction showed that the ThMn 12 -type structure is retained, but that the unit cell volume is slightly increased. More significantly, the nitrogenation has quenches the spin reorientations in TbTiFe 11 and DyTiFe 11 , and has made the easy magnetization directions (EMD) of their nitrides along the c axis from 0 K to Curie temperatures.