Study of the structural transition and hydrogenation of CeTiGe

International audienceThere remains some disagreement in the literature on CeTiGe over the presence of a structural transition from the low temperature CeFeSi-type form to the high temperature CeScSi-type structure. We present a detailed study of the effect of temperature on this structural transition. Furthermore, the same hydride is obtained after hydrogenation of both forms. Using neutron powder diffraction we find that the structure of CeTiGeH1.5 corresponds to a stuffed variant of the CeScSi-type structure with space group I4/mmm, a = 4.0785(1) Å and c = 17.1060(8) Å. The H atoms occupy both the Ce4 tetrahedral sites and the Ti4Ce square based pyramidal sites for a total hydrogen occupancy of 1.5 H f.u.−1. Preliminary examinations of the magnetic properties after hydrogenation reveal the onset of low temperature magnetic order around 3.5 K, suggesting for the first time a hydrogen induced magnetic order for an intermetallic with CeScSi-type structure

Hyper-reduced models of hyperelastic dissipative elastomer bushings

Rubber mount modeling in multibody simulation is crucial for accuracy in this type of calculation, and despite its importance, they are often underestimated in terms of modeling. The present work aims to develop and implement a finite element model suited for rubber behavior in large deformations, and apply hyperreduction techniques to evaluate the possibility of a direct implementation into a multibody simulation, or to generate a novel family of joint models. The article begins with the development and implementation of the material behavior, then a brief explanation on the implemented finite elements routine along with the hyper-reduction method used. An analysis of the results and an insight of future developments closes the article

Structural and magnetic properties of the ternary compounds Gd₂Sc₃X₄ with X = Si and Ge

X-ray diffraction on single crystal performed on Gd2Sc3Si4 reveals that this ternary silicide crystallizes as Gd2Sc3Ge4 in the orthorhombic Ce2Sc3Si4-type with a small deficiency in gadolinium leading to the formula Gd1.88(1)Sc3Si4. The structure is formed by [Gd2Sc3Si4] slabs with Si-Si interslab covalent bonds. The investigation of the Gd2Sc3Si4 and Gd2Sc3Ge4 compounds by magnetization, electrical resistivity and specific heat measurements reveals their antiferromagnetic behaviors; Gd2Sc3Si5 having a Néel temperature (48-52 K) higher than that observed (22-23 K) for Gd2Sc3Ge4

On the structural and magnetic properties of the ternary silicides Ce6M1.67Si3 (M = Co, Ni) and Ce5Ni1.85Si3

Contrary to that reported previously, the ternary silicide "Ce6Ni2Si3" does not exit. The melting of this alloy, followed or not by annealing, leads to the existence of the two ternary compounds..

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Around the composition Gd₄Co₃: Structural, magnetic and magnetocaloric properties of Gd₆Co_4.85(2)

Investigation of the Gd–Co system around the composition Gd4Co3 showed that this compound does not exist. When samples with the nominal composition Gd4Co3 are synthesized a mixture of Gd12Co7 and Gd6Co4.85(2) (=Gd4Co3.23(2)) is observed. Gd6Co4.85(2) is the only compound found around the composition Gd:Co = 4:3. Its structure was determined by means of X-ray diffraction on single crystal with the space group P63/m. The cell parameters are a = 11.593(2) Å and c = 4.0495(14) Å. Its structure is closely related to the Ho4Co3.07-type or to the Ce6Ni1.67Si3-type structure. Gd6Co4.85(2) exhibits only one ferro(ferri)magnetic transition at 219(1) K and the second magnetic transition at 163 K, wrongly attributed to a spin reorientation, corresponds indeed to the ferromagnetic transition of the impurity Gd12Co7. Gd6Co4.85(2) presents magnetocaloric properties with a maximal adiabatic temperature change ΔTad equal to 4.4 K for μ0ΔH = 4.5 T