Reduced Enthalpy of Metal Hydride Formation for Mg–Ti Nanocomposites Produced by Spark Discharge Generation.
Spark discharge generation was used to synthesize Mg–Ti nanocomposites consisting primarily of a metastable body-centered-cubic (bcc) alloy of Mg and Ti. The bcc Mg–Ti alloy transformed upon hydrogenation into the face-centered-cubic fluorite MgTiH phase with favorable hydrogen storage properties. B...
| Publicado en: | Journal of the American Chemical Society Vol. 135; no. 21; pp. 7891 - 7901 |
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| Autores principales: | , , , , , , , |
| Formato: | Artículo |
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American Chemical Society
5/29/2013
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| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=88117880&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 88117880 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 5/29/2013 vid: 135 iid: 21 pid: 997 pub: American Chemical Society artinfo: ui: 88117880 10.1021/ja3123416 ppf: 7891 ppct: 10 formats: tig: atl: Reduced Enthalpy of Metal Hydride Formation for Mg–Ti Nanocomposites Produced by Spark Discharge Generation. aug: au: Anastasopol, Anca Pfeiffer, Tobias V. Middelkoop, Joost Lafont, Ugo Canales-Perez, Roger J. Schmidt-Ott, Andreas Mulder, Fokko M. Eijt, Stephan W. H. affil: Fundamental Aspects of Materials and Energy, Department of Radiation, Radionuclides and Reactors, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands NanoStructured Materials, Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands Materials for Energy Conversion and Storage, Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands Novel Aerospace Materials, Department of Aerospace Structures and Materials, Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands su: Hydrides Synthesis of Nanocomposite materials Heat of formation Magnesium alloys Titanium alloys Electrostatic discharges Hydrogenation Grain refinement sug: subj: Hydrides Synthesis of Nanocomposite materials Heat of formation Magnesium alloys Titanium alloys Electrostatic discharges Hydrogenation Grain refinement ab: Spark discharge generation was used to synthesize Mg–Ti nanocomposites consisting primarily of a metastable body-centered-cubic (bcc) alloy of Mg and Ti. The bcc Mg–Ti alloy transformed upon hydrogenation into the face-centered-cubic fluorite MgTiH phase with favorable hydrogen storage properties. Both metal and metal hydride nanocomposites showed a fractal-like porous morphology, with a primary particle size of 10–20 nm. The metal content of 70 atom % (at %) Mg and 30 at % Ti, consistently determined by XRD, TEM-EDS, and ICP-OES, was distributed uniformly across the as-prepared sample. Pressure–composition isotherms for the Mg–Ti–H nanocomposites revealed large differences in the thermodynamics relative to bulk MgH, with a much less negative enthalpy of formation of the hydride as small as -45 ± 3 kJ/mol H as deduced from van’t Hoff plots. The plateau pressures of hydrogenation were substantially higher than those for bulk MgH in the low temperature range from 150 to 250 °C. The reaction entropy was simultaneously reduced to values down to 84 ± 5 J/K mol H, following a linear relationship between the enthalpy and entropy. Plausible mechanisms for the modified thermodynamics are discussed, including the effect of lattice strains, the presence of interfaces and hydrogen vacancies, and the formation of excess free volume due to local deformations. These mechanisms all rely on the finely interdispersed nanocomposite character of the samples which is maintained by grain refinement. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2013 holdings: @attributes: islocal: N |
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