Hydrogen sorption properties of V85Ni15 |
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Authors: | S Tosti A Santucci A Pietropaolo S Brutti O Palumbo F Trequattrini A Paolone |
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Affiliation: | 1. Dipartimento Fusione e Tecnologie per la Sicurezza Nucleare, ENEA, Via E. Fermi 45, 00044 Frascati, RM, Italy;2. CNR-ISC, U.O.S. Sapienza, Piazzale A. Moro 5, 00185 Roma, Italy;3. Dipartimento di Scienze, Università della Basilicata, V.le Ateneo Lucano 10, 85100 Potenza, Italy;4. Dipartimento di Fisica, Università di Roma La Sapienza, P.le Aldo Moro 5, 00185 Roma, Italy |
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Abstract: | An alloy with nominal composition V85Ni15 was prepared in a vacuum induction melting apparatus. The chemical analysis of the sample showed a V (Ni) content of 82.63 (15.68) at% and small contaminations by carbon and aluminum. XRD measurements confirmed that the bcc Ni-V solid solution phase is the main constituent of the sample. However, a minor impurity (approximately 6.5 wt%) due to the precipitation of the sigma NiV3-x phase is present in the sample.Hydrogen sorption measurements extending from 150 °C up to 400 °C in a wide pressure range (up to 90 bar) were performed. Upon hydrogenation below 250 °C, one observes the subsequent presence of an α phase and of two hydride phases with different values of dehydrogenation enthalpy: ΔHdehydr = 21 ± 1 kJ/mol for 0.15 ≤ H/M ≤ 0.30 and ΔHdehydr = 26 ± 2 kJ/mol for 0.53 ≤ H/M ≤ 0.59. Above 300 °C, there is no evidence of the formation of hydrides and only an α phase is present up to the maximum measured composition, with a hydrogenation enthalpy ΔHhydr = 10.0 ± 0.5 kJ/mol. |
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Keywords: | V-Ni alloys Hydrogen sorption Solid solution Hydride Hydrogenation enthalpy |
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