arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0707.4604cond-mat.mtrl-sci
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gamma-AlH3的电子和振动性质

Electronic and Vibrational Properties of gamma-AlH3

Yan Wang, Jia-An Yan, M. Y. Chou

摘要:

氢化铝AlH_3是一种重要的储氢材料。AlH_3以多晶型存在,其中$α$ -AlH_3最稳定,具有六方结构。最近对$γ$ -AlH_3的实验研究表明,它是一种正交晶系结构,在Al和H原子之间存在独特的双桥键。这在$α$ -AlH_3或其它多晶型物中未发现。本文用密度泛函理论研究了新报道的$γ$ -AlH_3结构的能量、结构、电子和声子振动性质。计算结果表明,$γ$ -AlH_3的稳定性比$α$ -AlH_3低2.1 KJ/mol.有趣的绑定功能与独特的几何$γ$ -AlH 3的电子性质和声子振动模式的计算进行了讨论。H-s与高能Al-p,d轨道的结合在双桥排列中得到增强,从而为系统带来更高的电子能量。$γ$ -AlH_3体系的振动光谱中出现了一些新的特征,它们是由双桥和六方环结构引起的。

英文摘要:

Aluminum hydride (alane) AlH_3 is an important material in hydrogen storage applications. It is known that AlH_3 exists in multiply forms of polymorphs, where $α$-AlH_3 is found to be the most stable with a hexagonal structure. Recent experimental studies on $γ$-AlH_3 reported an orthorhombic structure with a unique double-bridge bond between certain Al and H atoms. This was not found in $α$-AlH_3 or other polymorphs. Using density functional theory, we have investigated the energetics, and the structural, electronic, and phonon vibrational properties for the newly reported $γ$-AlH_3 structure. The current calculation concludes that $γ$-AlH_3 is less stable than $α$-AlH_3 by 2.1 KJ/mol. Interesting binding features associated with the unique geometry of $γ$-AlH3 are discussed from the calculated electronic properties and phonon vibrational modes. The binding of H-s with higher energy Al-p,d orbitals is enhanced within the double-bridge arrangement, giving rise to a higher electronic energy for the system. Distinguishable new features in the vibrational spectrum of $γ$-AlH_3 were attributed to the double-bridge and hexagonal-ring structures.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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