[Sans titre]
| hal.structure.identifier | Laboratory of Crystallography | |
| dc.contributor.author | CERNY, Radovan | |
| hal.structure.identifier | Laboratory of Crystallography | |
| hal.structure.identifier | Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB] | |
| dc.contributor.author | PENIN, Nicolas | |
| hal.structure.identifier | Laboratory of Crystallography | |
| dc.contributor.author | D'ANNA, Vincenza | |
| hal.structure.identifier | Department of Physical Chemistry | |
| dc.contributor.author | HAGEMANN, Hans | |
| hal.structure.identifier | Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB] | |
| dc.contributor.author | DURAND, Etienne | |
| hal.structure.identifier | Department of Inorganic Chemistry | |
| dc.contributor.author | RUZICKA, Jakub | |
| dc.date.issued | 2011 | |
| dc.identifier.issn | 1359-6454 | |
| dc.description.abstractEn | A solid solution of magnesium and manganese borohydrides was studied by in situ synchrotron radiation X-ray powder diffraction and infrared spectroscopy. A combination of thermogravimetry, mass and infrared spectroscopy, and atomic emission spectroscopy were applied to clarify the thermal gas desorption of pure Mn(BH<sub>4</sub>)<sub>2</sub> and a solid solution of composition Mg<sub>0.5</sub>Mn<sub>0.5</sub>(BH<sub>4</sub>)<sub>2</sub>. Mg<i><sub>x</sub></i>Mn<sub>(1−</sub><i><sub>x</sub></i><sub>)</sub>(BH<sub>4</sub>)<sub>2</sub> (<i>x = </i>0-0.8) conserves the trigonal structure of Mn(BH<sub>4</sub>)<sub>2</sub> at room temperature. Manganese is dissolved in the hexagonal structure of α-Mg(BH<sub>4</sub>)<sub>2</sub>, with the upper solubility limit not exceeding 10 mol.% at room temperature. There exists a two-phase region of trigonal and hexagonal borohydrides within the compositional range <i>x </i>= 0.8-0.9 at room temperature. Infrared spectra show splitting of various vibrational modes, indicating the presence of two cations in the trigonal Mg<i><sub>x</sub></i>Mn<sub>(1−</sub><i><sub>x</sub></i><sub>)</sub>(BH<sub>4</sub>)<sub>2</sub> solid solutions, as well as the appearance of a second phase, hexagonal α-Mg(BH<sub>4</sub>)<sub>2</sub>, at higher magnesium contents. All vibrational frequencies are shifted to higher values with increasing magnesium content. The decomposition temperature of the trigonal Mg<i><sub>x</sub></i>Mn<sub>(1−</sub><i><sub>x</sub></i><sub>)</sub>(BH<sub>4</sub>)<sub>2</sub> (<i>x = </i>0-0.8) does not vary significantly as a function of the magnesium content (433-453 K). The desorbed gas contains mostly hydrogen and 3-7.5 mol.% diborane B<sub>2</sub>H<sub>6</sub>, as determined from analyses of the Mn(BH<sub>4</sub>)<sub>2</sub> and Mg<sub>0.5</sub>Mn<sub>0.5</sub>(BH<sub>4</sub>)<sub>2</sub> samples. An eutectic relation between α-Mg(BH<sub>4</sub>)<sub>2</sub> and LiBH<sub>4</sub> is observed. The solid solution Mg<i><sub>x</sub></i>Mn<sub>(1−</sub><i><sub>x</sub></i><sub>)</sub>(BH<sub>4</sub>)<sub>2</sub> is a promising material for hydrogen storage as it decomposes at a similar temperature to Mn(BH<sub>4</sub>)<sub>2</sub>, i.e. at a much lower temperature than pure Mg(BH<sub>4</sub>)<sub>2</sub> without significantly losing hydrogen weight capacity thanks to substitution of Mn by Mg up to 80 mol.%. The questions of diborane release and reversibility remain to be addressed. | |
| dc.language.iso | en | |
| dc.publisher | Elsevier | |
| dc.subject.en | Hydrides | |
| dc.subject.en | Hydrogen storage | |
| dc.subject.en | Synchrotron radiation | |
| dc.type | Article de revue | |
| dc.identifier.doi | 10.1016/j.actamat.2011.04.052 | |
| dc.subject.hal | Chimie/Matériaux | |
| bordeaux.journal | Acta Materialia | |
| bordeaux.page | 5171-5180 | |
| bordeaux.volume | 59 | |
| bordeaux.issue | 13 | |
| bordeaux.peerReviewed | oui | |
| hal.identifier | hal-00606790 | |
| hal.version | 1 | |
| hal.popular | non | |
| hal.audience | Internationale | |
| hal.origin.link | https://hal.archives-ouvertes.fr//hal-00606790v1 | |
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