From qualitative to quantitative description of the anomalous thermoelastic behavior of V, Nb, Ta, Pd and Pt
From qualitative to quantitative description of the anomalous thermoelastic behavior of V, Nb, Ta, Pd and Pt
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DOI：
10.1088/1361-648x/ab099b
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
Philipp Keuter;D. Music;V. Schnabel;M. Stuer;J. Schneider
中科院分区：
文献类型：
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作者：
Philipp Keuter;D. Music;V. Schnabel;M. Stuer;J. Schneider
为了研究bcc V、Nb、Ta以及fcc Pd和Pt的异常热弹性行为，使用基于密度泛函理论（DFT）的模型，其允许计算弹性常数并作为温度的函数。可用的实验趋势正确地再现表明，电子结构机制，使异常行为被捕获的模型。基于密度泛函理论的V，Nb，Ta，Pd和Pt与异常热弹性性质和Mo和Cu与正常行为之间的相关性研究表明，在费米能级的高态密度（DOS）是一个必要的，但不是充分条件的异常热弹性行为。此外，与普通金属相反，反常金属在晶格畸变时重新分配费米能级附近的电子态，导致键强度增加，如通过晶体轨道汉密尔顿布居（COHP）分析所确定的。因此，我们已经确定了高DOS和晶格畸变后的电子再分配的组合是金属中异常热弹性行为的物理起源。在V，Nb，Ta，Pd和Pt的异常型失真的情况下，建议是由于不太明显的重新分配的状态相比，型失真。
To study the anomalous thermoelastic behavior of bcc V, Nb, Ta as well as fcc Pd and Pt a density functional theory (DFT) based model is used, which allows for the calculation of the elastic constant and as a function of temperature. Available experimental trends are correctly reproduced indicating that the electronic structure mechanisms enabling anomalous behavior are captured by the model. A DFT based correlative investigation between V, Nb, Ta, Pd and Pt with anomalous thermoelastic properties and Mo and Cu with ordinary behavior reveals a high density of states (DOS) at the Fermi level to be a necessary but not sufficient condition for an anomalous thermoelastic behavior. In addition, anomalous metals in contrast to ordinary metals reallocate electronic states in the vicinity of the Fermi level upon lattice distortion, causing an increase in bond strength as identified by crystal orbital Hamilton population (COHP) analysis. Hence, we have identified the combination of high DOS and electronic reallocation upon lattice distortion to be the physical origin for anomalous thermoelastic behavior in metals. The absence of an anomaly for -type distortion in V, Nb, Ta, Pd and Pt is suggested to be due to the less pronounced reallocation of states compared to -type distortion.