Halide Substitution in Magnesium Borohydride

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• 作者：Satoshi Hino ; Jon Erling Fonnel酶p ; Marta Corno ; Olena Zavorotynska ; Alessandro Damin ; Bo Richter ; Marcello Baricco ; Torben R. Jensen ; Magnus H. S酶rby ; Bj酶rn C. Hauback
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：June 14, 2012
• 年：2012
• 卷：116
• 期：23
• 页码：12482-12488
• 全文大小：388K
• 年卷期：v.116,no.23(June 14, 2012)
• ISSN：1932-7455

文摘

The synthesis of halide-substituted Mg(BH₄)₂ by ball-milling, and characterization with respect to thermodynamics and crystal structure, has been addressed. The ball-milled mixture of Mg(BH₄)₂ and MgX₂ (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 尾-Mg(BH₄)₂ in milled and annealed mixtures of Mg(BH₄)₂ with MgCl₂/MgBr₂ is smaller than that of pure 尾-Mg(BH₄)₂. This is due to substitution of BH₄^{鈥?/sup> by Cl鈥?/sup>/Br鈥?/sup> ions which have ionic radii smaller than that of BH₄鈥?/sup>. For comparison, ab initio calculations were run to simulate Cl substitution in 伪-Mg(BH₄)₂. The 伪-polymorph was used rather than the 尾-polymorph because the size of the unit cell was more manageable. Electronic energy data and thermodynamic considerations confirm the miscibility of MgCl₂ and Mg(BH₄)₂, both in 伪- and 尾-polymorphs.}