Rare-earth RE Research Articles

Ferromagnetic properties of U 2M 17− yGe y systems (M ≡ Fe, Co)

The ternary germanides U 2M 17− y Ge y were synthesized respectively with 2 ⩽ y ⩽ 3 for M ≡ Fe and 1.3 ⩽ y ⩽ 3 for M ≡ Co. These compounds crystallize in the hexagonal Th 2Ni 17-type structure. Rietveld X-ray diffraction study indicates a strong preferential site occupation of Ge atoms on one (12k) of the four different transition element sites of this type of structure. All the compounds order ferromagnetically with a Curie temperature T C going through a maximum at T C = 545(5) K for y = 2.5 with increasing Ge content in the U 2Fe 17− y Ge y system, whereas T C decreases linearly as y increases for the U 2Co 17− y Ge y system. Also, the effect of the substitution of Co for Fe in U 2(Fe 14.5− x Co x )Ge 2.5 alloys on their structural and magnetic properties was investigated. The results are compared with those obtained for the intermetallic compounds based on rare earth elements RE 2Fe 17 and RE 2Co 17.

Formation, crystal chemistry and magnetism of compounds RE 2TGe 6, RE  rare earth, T  Pd, Pt, Cu, Ag and Au

Novel ternary compounds RE 2TGe 6 (RE  Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb; T  Pd, Pt, Ag, Au) were synthesized by argon arc melting followed by a heat treatment at 600 or 800 °C for 150 h. From X-ray powder analysis all compounds were found to be isotypic with structure type Ce 2CuGe 6. Magnetic susceptibilities were measured for RE 2CuGe 6 (RE  Ce, Pr, Nd, Sm) and Ce 2PdGe 6. All compounds exhibit antiferromagnetic ordering below 20 K. The paramagnetic effective moments agree with the values for tripositive RE ion moments. The Sm containing sample reveals typical Van Vleck type paramagnetism above the Néel point.

Magnetic properties of some PtREIn (RE  rare earth) alloys

Abstract Magnetisation measurements are reported for the intermetallic alloys with composition PtREIn and with RE  Gd, Tb and Dy. The magnetic susceptibilities have been determined using powder samples and within the temperature range from 2 to 300 K. The magnetisation was determined in fields up to 5 T.

Characterization of local anisotropy and anisotropy dispersion of amorphous CoZrRE with rare earth REPr and Nd

The magnetic properties of rf sputtered amorphous (Co 93Zr 7) 100− x (RE) x thin films were investigated where REPr and Nd and for a content of 0 < x < 3.5 by Transverse Biased Initial Susceptibility measurements. Clear relationships could be established between K u and K loc. The data are discussed in terms of single-ion anisotropy of the RE.

On the crystal structure and magnetic properties of the ternary rare earth compounds RETSb2 with RE  rare earth and T  Ni, Pd, Cu and Au

Novel compounds RETSb2 have been prepared and characterized for T  Cu (RE  rare earth from La to Lu), Ni (RE  La to Ho), Pd (RE  La to Tb) and Au (RE  La to Sm). From X-ray powder diffraction analyses all compounds were found to crystallize as the ZrCuSi2 type. Magnetic susceptibilities were generally measured in the temperature range from 4 to 100 K. YCuSb2 and LaTSbz are temperature-independent paramagnets. RETSb2 compounds are found to order antiferromagnetically below T  20 K. PrPdSb2 and TbPdSb2 undergo metamagnetic transitions, whereas PrCuSb2 and ErCuSb2 are simple ferromagnets. The Sm-containing compounds are typical Van Vleck paramagnets owing to the closely spaced multiplets.

The crystal structure of CeRu 2B 2 and isotypic compounds M(Ru, Os) 2B 2, M = La, Pr, Nd, Sm, Gd, and Th

The crystal structure of CeRu 2B 2 has been determined from single-crystal X-ray counter data. The crystal structure of CeRu 2B 2 is closely related to the CaRh 2B 2-type structure. CeRu 2B 2 is face-centered orthorhombic with the lattice parameters: a = 6.4861(27), b = 9.0573(60), and c = 10.0263(27) Å, Z = 8. Due to small deviations from space group symmetry Fddd ( D 24 2 h ), the actual symmetry is F222 ( D 7 2). The structure was solved by Patterson methods and refined by full matrix least-squares calculations. For an asymmetric set of 217 independent reflections (| F o z. sfnc; > 2 σ( F o)), the obtained reliability factors were R = ∑z.sfnc;ΔFz.sfnc; ∑z.sfnc;F o z.sfnc; = 0.024, R w = 0.020 for the calculation in the higher symmetry space group Fddd. Isotypic compounds {RE, Th} {Ru, Os} 2B 2 have been synthesized with the light (ceric) rare-earth elements RE = La, Ce, Pr, Nd, Sm, and Gd and with thorium. The magnetic behavior of the cerium-containing borides Ce(Ru, Os) 2B 2 was studied in the temperature range from 1.6 to 1100 K. No superconductivity was observed. Practically no solubility was observed for silicon in CeRu 2B 2 and CeOs 2B 2 alloys (both as cast and annealed at 1100°C).

Magnetic properties of RENbF 7 (RE  rare earth)

The magnetic properties of the series RENbF 7 (RE  Ce, Pr, Nd, Gd, Dy, Ho, Er, Yb) were investigated. Magnetic susceptibility data were obtained on powdered samples at temperatures from 4.2 to 200 K. All compounds were found to be paramagnetic in this temperature range. Magnetization versus applied field curves for the materials with RE  Ce, Nd, Er, Yb could be fitted successfully to Brillouin functions with an effective spin of 1 2 ; for RE  Gd the expected free-ion behaviour was observed. The 70 170Yb Mössbauer spectrum of YbNbF 7 at 4.2 K showed a three-line pattern resulting from quadrupole interactions only. This observation is consistent with the absence of magnetic order at 4.2 K. Analysis of these data allows the conclusion that the ground state of the RE 3+ ion in these materials is characterized by large admixtures of wavefunctions of the form ¦J, ± M J( max) 〉.

Crystal structure of RENiSn and REPdsn (RE  rare earth) equiatomic compounds

The crystal structures of 19 ternary compounds were investigated by X-ray powder diffraction. The alloys were of (RE, Y)NiSn and REPdSn (RE  rare earth) equiatomic composition. The TiNiSi-type structure (oP12) was found.

Synthesis and structures of A 2REX 5-type halides (RE  rare earth)

Synthesis and structures of A 2REX 5-type halides (RE  rare earth)

Effect of rare earth metals and the stability of sulfide inclusions on Localized corrosion of low alloy steels

AbstractEffect of alloying with rare earth elements RE (La, Pd + Nd, or so called “Mischmetall” containing Ce, Pr, Nd, La and traces of the other RE) on the ability to passivate and susceptibility to chloride breakdown of low alloys steels was investigated. Electron microprobe analysis revealed that the effect of RE depends upon the element and is connected with a modification of the composition and morphology of MnS inclusions present within the steels without RE addition. La seems to be most detrimental. The nonstability of La sulfide inclusions in air results in their spontaneous oxidation and growth into fantastic “flower‐like” forms which facilitates the formation of corrosion pits.