Abstract
The synthesis of halide-substituted Mg(BH 4) 2 by ball-milling, and characterization with respect to thermodynamics and crystal structure, has been addressed. The ball-milled mixture of Mg(BH 4) 2 and MgX 2 (X = Cl, Br) has been investigated by in situ/ex situ synchrotron powder X-ray diffraction (SR-PXD), differential scanning calorimetry (DSC), and infrared and Raman spectroscopy. High resolution SR-PXD patterns reveal that the unit cell volume of β-Mg(BH 4) 2 in milled and annealed mixtures of Mg(BH 4) 2 with MgCl 2/MgBr 2 is smaller than that of pure β-Mg(BH 4) 2. This is due to substitution of BH 4 - by Cl -/Br - ions which have ionic radii smaller than that of BH 4 -. For comparison, ab initio calculations were run to simulate Cl substitution in α-Mg(BH 4) 2. The α-polymorph was used rather than the β-polymorph because the size of the unit cell was more manageable. Electronic energy data and thermodynamic considerations confirm the miscibility of MgCl 2 and Mg(BH 4) 2, both in α- and β-polymorphs.
Lingua originale | Inglese |
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pagine (da-a) | 12482-12488 |
Numero di pagine | 7 |
Rivista | Journal of Physical Chemistry C |
Volume | 116 |
Numero di pubblicazione | 23 |
DOI | |
Stato di pubblicazione | Pubblicato - 14 giu 2012 |
Pubblicato esternamente | Sì |