Experimental Evidence of Na2[B12H12] and Na Formation in the Desorption Pathway of the 2NaBH4 + MgH2 System

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• 作者：Sebastiano Garroni ; Chiara Milanese ; Daphiny Pottmaier ; Gabriele Mulas ; Pau Nolis ; Alessandro Girella ; Riccarda Caputo ; David Olid ; Francesc Teixdor ; Marcello Baricco ; Amedeo Marini ; Santiago Surin虄ach ; M. Dolors Baro虂
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：August 25, 2011
• 年：2011
• 卷：115
• 期：33
• 页码：16664-16671
• 全文大小：909K
• 年卷期：v.115,no.33(August 25, 2011)
• ISSN：1932-7455

文摘

In the present work we report the desorption pathway of the 2NaBH₄ + MgH₂ system. Ex-situ X-ray powder diffraction (XRPD) and solid state magic angle spinning (MAS) nuclear magnetic resonance (NMR) measurements have been performed on samples heat treated up to 450 掳C for different times. Ex-situ X-ray powder diffraction experiments conducted on fully desorbed samples allowed us to identify nanocrystalline MgB₂ and metallic Na as dehydrogenation products. ¹¹B and ²³Na NMR analyses have been also carried out in order to evaluate the structural evolution of decomposed materials. Our measurements show that the local structure of MgB₂ is influenced by replacement of Mg with Na atoms in the Mg sites. Moreover, amorphous Na₂[B₁₂H₁₂] was detected in the partially desorbed sample and in the final products of the decomposition reaction. The presence of the [B₁₂H₁₂]^{2鈥?/sup> anion was confirmed by both direct comparison with the 11B{1H} NMR spectrum of pure Na₂[B₁₂H₁₂] and dynamic cross-polarization experiments.}