β-锂霞石弹性常数的密度泛函理论研究
Elastic constants of beta-eucryptite: A density functional theory study
摘要：
用密度泛函理论（DFT）计算了六方$β$ -锂霞石的五个独立弹性常数。计算值与实验值吻合良好，在15%以内。使用计算的弹性常数，线性压缩$β$ -锂霞石平行于c轴，$χ_c$，和垂直于它，$χ_a$，已被评估。这些值与从实验已知的弹性常数获得的值非常一致，但与基于三端技术的直接测量值相矛盾。平行于c轴的计算压缩性被认为是积极的，而不是通过直接测量获得的负值。我们已经证明，$χ_c$必须是积极的，并讨论了一个积极的$χ_c$的背景下解释的负体积热膨胀的$β$ -锂霞石的影响。
英文摘要：
The five independent elastic constants of hexagonal $β$-eucryptite have been determined using density functional theory (DFT) total energy calculations. The calculated values agree well, to within 15%, with the experimental data. Using the calculated elastic constants, the linear compressibility of $β$-eucryptite parallel to the c-axis, $χ_c$, and perpendicular to it, $χ_a$, have been evaluated. These values are in close agreement to those obtained from experimentally known elastic constants, but are in contradiction to the direct measurements based on a three-terminal technique. The calculated compressibility parallel to the c-axis was found to positive as opposed to the negative value obtained by direct measurements. We have demonstrated that $χ_c$ must be positive and discussed the implications of a positive $χ_c$ in the context of explaining the negative bulk thermal expansion of $β$-eucryptite.
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