Papers by Author: N.E. Skryabina

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Authors: Elena Kurenkova, Anna Vyvodtseva, Marina G. Shelyapina, Vladimir I. Chizhik, Alexandr V. Ievlev, N.E. Skryabina, Anahit G. Aleksanyan, Daniel Fruchart
Abstract: According to 1H NMR study in fcc hydrides of disordered Ti-V alloys hydrogen atoms are distributed over both octahedral and tetrahedral sites. The occupancy of octahedral sites increases with the vanadium concentration. In hydrides of ternary Ti-V-Cr alloys hydrogen atoms occupy tetrahedral sites only.
Authors: N.E. Skryabina, Daniel Fruchart, Natalya A. Medvedeva, Patricia de Rango, Anastasiya A. Mironova
Abstract: TiVCr alloys known for their potentially large hydrogen uptake were formulated as (TiCr1.8)100-xVx in order to quantify the impact of vanadium concentration. Parallel to this series of pure ternary, a 2nd ones was synthesized with 4 at.% of Zr7Ni10 addition. Electrochemical charging with hydrogen reveals a fair dependence of hydrogen uptake and hydrides stability versus the x (V) content, moreover conversely different due to the presence of the Zr-Ni additive.
Authors: D. Boudemagh, Daniel Fruchart, R. Haettel, El Kebir Hlil, A. Lacoste, L. Ortega, N.E. Skryabina, Janusz Toboła, Pierre Wolfers
Abstract: Laves phases of C15 type of the system Mg2Si1-xSnx with x = 0, 0.4, 0.6 and 1 were synthesized in polycrystalline state in tantalum ampoule heated by high frequency coupling. The as-cast materials were analysed first at room temperature by X-ray diffraction (XRD). Systematically, XRD patterns were recorded up to 700 °C and Differential Scanning Calorimetry analysis was performed up to 1200°C to control the chemical and structural phase transformations. From these experiments, a C15 to C36 structure transformation was pointed out around 600°C in Mg2Si1-xSnx.solid solutions.
Authors: N.E. Skryabina, Daniel Fruchart, L. Cagnon, A.V. Shelyakov
Abstract: The creep deformation process initiated by hydrogen in both amorphous and nanocrystalline TiNi based alloys has been investigated. The mechanical behaviour has been interpreted in terms of microstructure phase transformations.
Authors: N.E. Skryabina, Lev Spivak, Daniel Fruchart
Authors: N.E. Skryabina, Daniel Fruchart, Salvatore Miraglia, Patricia de Rango, Marina G. Shelyapina
Abstract: Occurrence of phase transitions in TixVyCrz-H systems was analyzed versus temperature. Hydrogen evacuates from the hydrogenated compounds via two main steps. The 1st step corresponds to the destabilization of the fcc hydrogenated lattice leading to a fcc → bcc martensitic type transformation. The 2nd step occurs according to the decomposition of the resulting hydride via evacuation of hydrogen from the bcc lattice. Both the kinetics and temperature of 1st and 2nd step transformations depend on the composition of the starting TixVyCrz alloys.
Authors: N.E. Skryabina, Vladimir M. Pinyugzhanin, Daniel Fruchart
Abstract: In the most recent years, MgH2 has attracted considerable attention for reversible hydrogen storage purposes because of a large 7.6 w% H-uptake, single plateau reaction at low pressure and abundance of metal. If the Mg ↔ H reactions take place at rather high temperature (> 300°C), the kinetic remains very low. However, early transition metal based additives (Ti, V, Nb...) improve dramatically the kinetics of hydrogen absorption/desorption, while having no essential impact on the reversible sorption capacity. Systematic analysis of many experimental data led to question chemical, physical, mechanical... parameters contributing significantly to improve the kinetics of absorption/desorption. Besides, results of theoretical and numerical computation enlighten the impact of structural and mechanical parameters owing to the local bonds of Mg/MgH2 with of TM elements, in terms of total energy and electronic structure. More specifically, we found highly relevant to consider 1 - the impact of the crystallite sizes of Mg and the TM-phase, 2 - the role of internal and external stresses, as well as 3 - the role of texture on the kinetics of hydrogen absorption/desorption. Apart the previous considerations, we like to underline the role of specific TM in trapping intermediately hydrogen thus forming TMHx prior initiating the Mg ↔ MgH2 nucleation process.
Authors: J.M. Gil, Benilde F.O. Costa, Patricia de Rango, Daniel Fruchart, Salvatore Miraglia, N.E. Skryabina
Abstract: Perturbed Angular Correlation (PAC) measurements were performed at room temperature on samples of Hf7Ni10 and of Hf7Ni10 combined with TiV0.8Cr1.2, and at temperatures in the range from 17 K to 350 K in a concentrated hydride of the combined alloy. The PAC results show that the Hf7Ni10 intergranular phase becomes amorphous in the combination process. The results for the hydride composite show in the Hf7Ni10 phase the formation of a stable interstitial hydrogen state below 100 K and a smooth rearrangement of the hydrogen atoms position above 100 K,corresponding to a slow diffusion movemnet of a short-range nature. A second phase transition is observed at around 300 K, presumably to aphase precursor of the hydrogen desorption of the hydride.
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