Yong-Fan Ding

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.

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.

Neutron diffraction study of YFe10−xCoxMo2

YFe{sub 10{minus}{ital x}}Co{sub {ital x}}Mo{sub 2}(0 {le} {ital x} {le} 10) compounds were synthesized and studied by x-ray and neutron diffraction. Single phase samples with ThMn{sub 12}-type structure can be formed in the entire range of composition. Magnetic properties were studied at fields up to 70 kOe in the temperature range of 1.5 K to room temperature. X-ray diffraction analyses of aligned powders indicate that the easy magnetization direction is parallel to the {ital c} axis when {ital x}{le}6, and deviates from the {ital c} axis when {ital x}{ge}8. Neutron diffraction experiments show that the molybdenum atoms exhibit a strong preference for occupying the 8{ital i} sites, and cobalt atoms prefer to occupy the 8{ital f} and 8{ital j} sites.YFe10−xCoxMo2(0 ≤ x ≤ 10) compounds were synthesized and studied by x‐ray and neutron diffraction. Single phase samples with ThMn12‐type structure can be formed in the entire range of composition. Magnetic properties were studied at fields up to 70 kOe in the temperature range of 1.5 K to room temperature. X‐ray diffraction analyses of aligned powders indicate that the easy magnetization direction is parallel to the c axis when x≤6, and deviates from the c axis when x≥8. Neutron diffraction experiments show that the molybdenum atoms exhibit a strong preference for occupying the 8i sites, and cobalt atoms prefer to occupy the 8f and 8j sites.

Magnetic properties of Si-substituted Y2Fe17

Abstract Magnetic properties of the Si-substituted Y 2 Fe 17 have been investigated. The Curie temperature increases with increasing Si content although the unit cell volume decreases. The average Fe magnetic moment decreases with Si substitution, and the easy magnetization direction does not change. Neutron-diffraction showed that the Si atoms do not preferentially occupy the dumbbell site. The occupancy of Si atoms is very small for the 6g site, and almost statistical for the other three sites.

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.

Neutron diffraction study of Y2Fe14BN1−δ

Abstract The studies of the crystallographic and magnetic properties of R2Fe14BN1−δ, where R represents Nd and Y, have been carried out by neutron diffraction techniques and magnetic measurements. Upon nitrogenation, the tetragonal structure of R2Fe14B is retained, but the unit cell volume is slightly increased. The refinement of neutron data indicates the nitrogen atoms occupy the 4f interstices in the nitrite of Y2Fe14B. In the consequence of filling these interstices, the Curie temperatures of these nitrides are increased about 60 K, wheres, their saturation moments and anisotropy fields are a little inferior to their virginal counterparts. In order to explain the changes of the magnetic properties, we give a brief discussion about the relationship between the magnetic properties and the crystallographic structure of these nitrides.

Neutron diffraction study of substituted YBa2Cu2.85M0.15O7-δ

Abstract Samples of YBa2Cu2.85M0.15O7-δ (M=Ti, Mn, Fe, Co) have been prepared. A decrease of Tc value with increase of 3d electron number of the substituting element was observed. Neutron diffraction studies on the samples were carried out to learn the relationship between Tc and site occupation of the substituting atoms. The results show that Ti and Fe prefer to substitute for 2q-Cu, while Mn and Co prefer to substitute for 1a-Cu. Primary discussion was made.

Neutron diffraction study of Y(TiFeC)12

Abstract Structure measurements on the carbide Y(TiFeC)12 prepared by arc-melting were carried out by means of powder neutron diffraction. Data analysis by profile technique showed that the carbon atoms occupy the 8i sites in the ThMn12 type structure, substituting for some Fe atoms. The large electronegativity of carbon on the 8i sites explains the observed effect of carbon on the intrinsic magnetic properties of RTiFe11, which is completely different from that of the interstitial nitrogen.