arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.01809cond-mat.mtrl-sci
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Cu $_{12}$ Sb PDMATHAAB S $_{13}$高温相电子输运和结构性质的第一性原理研究

First-principles study of electronic transport and structural properties of Cu$_{12}$Sb$_4$S$_{13}$ in its high-temperature phase

Cono di Paola, Francesco Macheda, Savio Laricchia, Cedric Weber, Nicola Bonini

摘要:

我们提出了一个从头算研究的结构和电子输运性质的黝铜矿,Cu $_{12}$ Sb $_4$ S $_{13}$,在其高温相。我们展示了这种复杂的化合物可以被看作是一个半导体的fematinite样结构(Cu 3SbS 4)中的S-空位的有序排列的结果。我们的计算证实,S-空位是这种热电化合物中的天然掺杂机制,并揭示了晶体学上不等价的Cu原子周围类似的局部化学环境,从而揭示了这种化合物中XPS测量的争论。为了获得电输运性质作为温度的函数,我们使用Kubo-Greenwood公式应用于第一性原理分子动力学模拟的快照。这种方法对于有效地解释这种复杂晶体结构中电子和晶格振动之间的相互作用至关重要,在这种复杂晶体结构中,强非谐性在稳定高温相方面起着关键作用。我们的研究结果表明,塞贝克系数是在良好的协议与实验和声子限制电阻率显示的温度趋势,比较以及与广泛的实验数据。预测的下限电阻率原来是非常低的原始矿物在铜锑硫系统,但不太远,从文献报道的最低实验数据。结果表明,洛伦兹数大大低于从Wiedemann-Franz定律中的自由电子值所预期的值,从而提供了一种准确的方法来估计实验中电子和晶格对热导率的贡献,这在这种非常低的热导率晶体材料中具有重要意义。

英文摘要:

We present an ab initio study of the structural and electronic transport properties of tetrahedrite, Cu$_{12}$Sb$_4$S$_{13}$, in its high-temperature phase. We show how this complex compound can be seen as the outcome of an ordered arrangement of S-vacancies in a semiconducting fematinite-like structure (Cu3SbS4). Our calculations confirm that the S-vacancies are the natural doping mechanism in this thermoelectric compound and reveal a similar local chemical environment around crystallographically inequivalent Cu atoms, shedding light on the debate on XPS measurements in this compound. To access the electrical transport properties as a function of temperature we use the Kubo-Greenwood formula applied to snapshots of first-principles molecular dynamics simulations. This approach is essential to effectively account for the interaction between electrons and lattice vibrations in such a complex crystal structure where a strong anharmonicity plays a key role in stabilising the high-temperature phase. Our results show that the Seebeck coeffcient is in good agreement with experiments and the phonon-limited electrical resistivity displays a temperature trend that compares well with a wide range of experimental data. The predicted lower bound for the resistivity turns out to be remarkably low for a pristine mineral in the Cu-Sb-S system but not too far from the lowest experimental data reported in literature. The Lorenz number turns out to be substantially lower than what expected from the free-electron value in the Wiedemann-Franz law, thus providing an accurate way to estimate the electronic and lattice contributions to the thermal conductivity in experiments, of great significance in this very low thermal conductivity crystalline material.

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