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arXiv 0909.4988cond-mat.mtrl-sci
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碱金属硅酸盐玻璃中的阳离子能量景观:性质和相关性

The cationic energy landscape in alkali silicate glasses: properties and relevance

H. Lammert, R. D. Banhatti, A. Heuer

摘要:

从碱金属硅酸盐玻璃的分子动力学模拟中明确地确定了单个阳离子位点的能量,并研究了这种局部能量与离子输运的性质和相关性。在离子输运的时间尺度上没有弛豫证明了能量景观的静态描述的有效性,因为它通常用于跳跃模型。阳离子之间的库仑相互作用是获得与典型的简化跳跃模型一致的平均能量景观所必需的。邻近地点之间以及同一地点的不同能量贡献之间都存在强相关性,它们塑造了能量景观的基本特征。一个模型的能量景观与一个单一的空缺是用来证明为什么平均网站-能量,包括充分的库仑相互作用,仍然不足以描述网站人口的离子,或他们的动态。这个模型解释了能量学和离子动力学之间的关系是如何被削弱的,从而最终确定了具有静态能量的跳跃图像无法捕获所有相关信息。因此,建议需要替代的简化模型的离子传导。

英文摘要:

Individual cationic site--energies are explicitly determined from molecular dynamics simulations of alkali silicate glasses, and the properties and relevance of this local energetics to ion transport are studied. The absence of relaxations on the timescale of ion transport proves the validity of a static description of the energy landscape, as it is generally used in hopping models. The Coulomb interaction among the cations turns out essential to obtain an average energy landscape in agreement with typical simplified hopping models. Strong correlations exist both between neighboring sites and between different energetic contributions at one site, and they shape essential characteristics of the energy landscape. A model energy landscape with a single vacancy is used to demonstrate why average site--energies, including the full Coulomb interaction, are still insufficient to describe the site population of ions, or their dynamics. This model explains how the relationship between energetics and ion dynamics is weakened, and thus establishes conclusively that a hopping picture with static energies fails to capture all the relevant information. It is therefore suggested that alternative simplified models of ion conduction are needed.

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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