4 research outputs found

    Changing the dehydrogenation pathway of LiBH4-MgH2via nanosized lithiated TiO2

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    Nanosized lithiated titanium oxide (LixTiO2) noticeably improves the kinetic behaviour of 2LiBH4 + MgH2. The presence of LixTiO2 reduces the time required for the first dehydrogenation by suppressing the intermediate reaction to Li2B12H12, leading to direct MgB2 formation.Fil: Puszkiel, Julián Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Castro Riglos, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Karimi, F.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Santoru, A.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Pistidda, C.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Klassen, T.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Bellosta von Colbe, J. M.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Dornheim, M.. Helmholtz-zentrum Geesthacht; Alemani

    On the thermal stability of ultrafine-grained Al stabilized by in-situ amorphous Al2O3 network

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    Bulk Al materials with average grain sizes of 0.47 and 2.4μm, were fabricated by quasi-isostatic forging consolidation of two types of Al powders with average particle sizes of 1.3 and 8.9μm, respectively. By utilizing the native amorphous Al2O3 (am-Al2O3) film on the Al powders surfaces, a continuous, ~7nm thick, am-Al2O3 network was formed in situ in the Al specimens. Systematic investigation of the changes to the am-Al2O3 network embedded in the Al matrix upon heating and annealing up to 600°C was performed by transmission electron microscopy (TEM). At the same time, the stability of the Al grain structure was studied by transmission Kikuchi diffraction (TKD), electron back-scatter diffraction (EBSD), and TEM. The am-Al2O3 network remained stable after annealing at 400°C for 24h. In-situ TEM studies revealed that at temperatures ≥450°C, phase transformation of the am-Al2O3 network to crystalline γ-Al2O3 particles occurred. After annealing at 600°C for 24h the transformation was completed, whereby only nanometric γ-Al2O3 particles with an average size of 28nm resided on the high angle grain boundaries of Al. Due to the pinning effect of γ-Al2O3, the Al grain and subgrain structures remained unchanged during annealing up to 600°C for 24h. The effect of the am-Al2O3→γ-Al2O3 transformation on the mechanical properties of ultrafine- and fine-grained Al is discussed from the standpoint of the underlying mechanisms.Fil: Balog, Martin. Slovak Academy of Sciences; Eslovaquia. University of California at Davis; Estados UnidosFil: Hu, Tao. University of California at Davis; Estados UnidosFil: Krizik, Peter. Slovak Academy of Sciences; EslovaquiaFil: Castro Riglos, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Saller, Brandon D.. University of California at Davis; Estados UnidosFil: Yang, Hanry. University of California at Davis; Estados UnidosFil: Schoenung, Julie M.. University of California at Davis; Estados UnidosFil: Lavernia, Enrique J.. University of California at Davis; Estados Unido

    A novel catalytic route for hydrogenation-dehydrogenation of 2LiH + MgB2: Via in situ formed core-shell LixTiO2 nanoparticles

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    Aiming to improve the hydrogen storage properties of 2LiH + MgB2 (Li-RHC), the effect of TiO2 addition to Li-RHC is investigated. The presence of TiO2 leads to the in situ formation of core-shell LixTiO2 nanoparticles during milling and upon heating. These nanoparticles markedly enhance the hydrogen storage properties of Li-RHC. Throughout hydrogenation-dehydrogenation cycling at 400 °C a 1 mol% TiO2 doped Li-RHC material shows sustainable hydrogen capacity of ∼10 wt% and short hydrogenation and dehydrogenation times of just 25 and 50 minutes, respectively. The in situ formed core-shell LixTiO2 nanoparticles confer proper microstructural refinement to the Li-RHC, thus preventing the material's agglomeration upon cycling. An analysis of the kinetic mechanisms shows that the presence of the core-shell LixTiO2 nanoparticles accelerates the one-dimensional interface-controlled mechanism during hydrogenation owing to the high Li+ mobility through the LixTiO2 lattice. Upon dehydrogenation, the in situ formed core-shell LixTiO2 nanoparticles do not modify the dehydrogenation thermodynamic properties of the Li-RHC itself. A new approach by the combination of two kinetic models evidences that the activation energy of both MgH2 decomposition and MgB2 formation is reduced. These improvements are due to a novel catalytic mechanism via Li+ source/sink reversible reactions.Fil: Puszkiel, Julián Atilio. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear. Gerencia Materiales.; Argentina. Helmholtz–Zentrum Geesthacht; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Castro Riglos, Maria Victoria. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Física de Metales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Ramallo Lopez, Jose Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Mizrahi, Martin Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Karimi, F.. Helmholtz–Zentrum Geesthacht; AlemaniaFil: Santoru, Antonio. Helmholtz–Zentrum Geesthacht; AlemaniaFil: Hoell, Armin. Helmholtz-zentrum Berlin; AlemaniaFil: Gennari, Fabiana Cristina. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear. Gerencia Materiales.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Arneodo Larochette, Pierre Paul. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear. Gerencia Materiales.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Pistidda, Claudio. Helmholtz–Zentrum Geesthacht; AlemaniaFil: Klassen, Thomas. Helmut Schmidt University; AlemaniaFil: Bellosta Von Colbe, J.M.. Helmholtz–Zentrum Geesthacht; AlemaniaFil: Dornheim, M.. Helmholtz–Zentrum Geesthacht; Alemani
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