[en] A.c. susceptibility measurements were carried out between 4.2 and 295 K on HoFe₁₁TiH and reveal a spin-reorientation transition at ∼150 K. Iron-57 Moessbauer spectral measurements between 4.2 and 295 K were carried out on both HoFe₁₁Ti and HoFe₁₁TiH. The Moessbauer spectra were analyzed with a model which considers both the orientation of the iron magnetic moments and the distribution of titanium atoms in the near-neighbor environment of the three crystallographically distinct iron sites. The assignment and the temperature dependence of the hyperfine fields is in complete agreement with both the iron magnetic moments measured by neutron diffraction and the changes expected at the spin-reorientation. The assignment and the temperature dependence of the isomer shifts is in complete agreement both with the crystallographic changes occurring at the spin reorientation and upon hydrogen insertion. The changes in hyperfine field and isomer shift with the number of titanium near neighbors for each of the three iron sites are consistent with the values observed for related titanium-iron intermetallic compounds

[en] The lattice parameters, magnetic and Moessbauer spectral properties of PrFe₁₁Ti and PrFe₁₁TiH have been measured between 4.2 and 295 K. Both compounds crystallize in the ThMn₁₂-type structure. The insertion of hydrogen in PrFe₁₁Ti anisotropically expands the unit-cell volume by 0.4%. Both compounds are ferromagnetically ordered with Curie temperatures of 547 and 604 K, respectively. Between 4.2 and 295 K, the easy magnetization direction is within the basal plane along the [1 0 0] direction as indicated by the Moessbauer spectra which have been fit with a model taking into account both the binomial distribution of titanium near neighbors of the iron atoms and the basal orientation of the magnetic moments

[en] Iron-57 Moessbauer spectral measurements between 4.2 and 295 K have been carried out on GdFe₁₁Ti and GdFe₁₁TiD and analyzed with a model which considers both the uniaxial magnetic anisotropy and the distribution of titanium atoms in the near-neighbor environment of the three crystallographically distinct iron sites. The assignment and the temperature dependencies of the hyperfine fields and isomer shifts are in complete agreement with the Wigner-Seitz cell analysis of the three iron sites in GdFe₁₁Ti and GdFe₁₁TiD. The changes in hyperfine field and isomer shift with the number of titanium near neighbors of the three iron sites are in agreement with the values observed for related titanium-iron intermetallic compounds. The hyperfine parameters also agree with those observed in other RFe₁₁Ti compounds and their hydrides

[en] The temperature dependence of the AC magnetic susceptibility, between 4.2 and 300 K, and the magnetization, between 300 and 600 K, has been measured for DyFe₁₁Ti and DyFe₁₁TiH. Iron-57 Moessbauer spectral measurements between 4.2 and 295 K have also been carried out on DyFe₁₁Ti and DyFe₁₁TiH and analyzed with a model which considers both the direction of the magnetization in the different magnetic phases of these compounds and the distribution of titanium atoms in the near-neighbor environment of the three crystallographically distinct iron sites. The magnetic measurements and the Moessbauer spectra of DyFe₁₁Ti clearly show the influence of the two spin reorientations occurring in this compound and indicate that the iron magnetic moments are oriented along the [1 0 0] direction of the basal plane below 100 K. The magnetic measurements and the Moessbauer spectra of DyFe₁₁TiH do not show any evidence for spin reorientations and are consistent with a basal magnetic anisotropy between 4.2 and 600 K. Hence, the hydrogen insertion into DyFe₁₁Ti reinforces the dysprosium magnetic anisotropy. The assignment and the temperature dependencies of the Moessbauer spectral hyperfine fields and isomer shifts are in full agreement with a Wigner-Seitz cell analysis of the three iron sites in DyFe₁₁Ti and DyFe₁₁TiH

[en] In this work are presented the summaries of the 19 symposiums presented at the conference: 'Materials 2014' and whose topics were: eco-materials, materials for energy storage and conversion, strategic materials, rare elements and recycling, surfaces functionalization and physico-chemical characterization, interfaces and coatings, corrosion, aging, durability, damage mechanical behaviours, disordered materials, glasses and their functionalization, materials and health, functional materials, porous, granular and with a high surface area materials, nano-materials, nano-structured systems, assembling processes, carbonaceous materials, great instruments and studies of materials, materials in severe conditions, powder forming processes, metallic materials and structures lightening. (O.M.)

[en] A NdCr₂Si₂C polycrystal has been prepared and characterized by heat-capacity and magnetization, X-ray and neutron powder diffraction measurements. Ferromagnetism below T_C = 21 K with Nd magnetic moments aligned parallel to the c-axis has been confirmed. We also studied the electronic structure of NdCr₂Si₂C by first-principles calculations, which predict the ordered magnetic moment both on the Nd and Cr sites. The magnetization and neutron diffraction data, however, do not allow resolving the question of existence of the Cr moment unambiguously.

[en] Transports of radioactive materials are regularly performed in an international context and the possibility of accidents with cross-border consequences cannot be excluded. Therefore, there is a need to harmonize emergency response or at least to have a clear understanding of other countries emergency plans. To that end, it was proposed to consider this topic in the framework of the European project PREPARE and to include various objectives relative to the off-site nuclear emergency response and preparedness in European countries notably in case of transport accident. The first step of this project was to clearly describe the national and local emergency organization and preparedness in the European countries participating to the project (France, United Kingdom and Belgium) especially in case of accident involving a transport of radioactive material. The second step of this project was to test, in case of an accident scenario involving an international transport of radioactive material, the emergency plans applied and the communications between two neighboring countries (France and Belgium). A table top exercise was organized to evaluate the accident management process including, on the one hand all phases relative to alerts, reflex actions, information exchange and concerted assessment, on the other hand public information and solution to bring back the transport in a safe status. This exercise, the first involving an international transport of radioactive materials, took place in the Emergency Technical Centre of IRSN located in Fontenay-aux-Roses in France. More than 30 peoples were involved including representatives of the Belgian competent authority (Federal Agency for Nuclear Control - FANC), the French Nuclear Safety Authority (ASN) as well as their Technical Safety Organizations (TSO), respectively BEL V and IRSN, and the major French operator AREVA TN International. Lessons learned from this experience allowed participants to create a feedback and highlighted the importance of communication between competent authorities and the necessary coordination of local intervention teams. (author)

[en] The crystal and magnetic structures of Y_n+1Co_3n+5B_2n (n=2, 3 and ∞) have been studied by high-resolution powder neutron diffraction. The results are compared to earlier measurements on YCo₅ and YCo₄B. A change in the regular stacking of the boron-containing plane along the c axis has been observed in the Y₂Co₇B₃ sample. Very short Co-B distances are observed, indicating that strong bonds are formed between cobalt and boron. The YCo₃B₂ compound is paramagnetic down to 2 K. The magnetic structures of Y₃Co₁₁B₄ and Y₂Co₇B₃ confirm the large variety of cobalt magnetic moments obtained in these compounds. The magnetic behaviour of the Co(2c) atoms is not significantly affected by the substitution of boron for cobalt. Cobalt atoms with significantly reduced magnetic moments are found on the 3g and 6i₂ sites in both Y₃Co₁₁B₄ and Y₂Co₇B₃. A relationship between the magnitude of the Co magnetic moment and the presence of boron in the neighbourhood of the cobalt atoms is proposed. The hybridization of the cobalt 3d electronic state with the boron 2p state is found to play a major role in the determination of the magnitude of the Co magnetic moment in the Y_n+1Co_3n+5B_2n compounds. (author)

[en] Detailed theoretical and experimental investigations on the electronic and magnetic properties of the Th _xY_1-xCo₄B compounds have been performed. All investigations of the electronic, magnetic and structural properties have been done using the fully relativistic spin polarized Korringa-Kohn-Rostoker (SPR-KKR) band structure method in ferromagnetic state. The disorder in the system has been accounted for by means of the Coherent Potential Approximation (CPA). The ThCo₄B compound orders ferromagnetically at 303 K, whilst the isotypic YCo₄B compound has a higher Curie temperature (380 K). The SPR-KKR calculated total magnetic moment decrease with Th concentration from 2.49 μ_B/f.u. for YCo₄B to 1.64 μ_B/f.u. for ThCo₄B. The magnetization measurements show a similar decrease of the magnetic moment with Th content from 2.90 μ_B/f.u. for YCo₄B to 1.49 μ_B/f.u. for ThCo₄B. The values of the Co magnetic moments depend strongly on the local environment. The preferential occupation of the Th/Y atoms evidenced by X-ray and neutron scattering experiments is investigated by theoretical calculations. In addition, the influence of the preferential occupation on the magnetic properties of the system is discussed

[en] We report a study of the evolution of the structure of the delafossite-derived compounds YCuO_2+δ as a function of oxygen stoichiometry. The structural details of the oxygenated material YCuO_2.5 were examined by means of high-resolution neutron powder diffraction. We confirmed that YCuO_2.5 adopts an orthorhombic superstructure (a = √3a_H, b=c_H, c=2a_H) in which the anions are located at the center of corner-sharing triangles to form undulating chains of Cu²⁺ (s=1/2), running along a-axis direction