Exceptionally low thermal conductivity realized in the chalcopyrite CuFeS2 via atomic-level lattice engineering
Exceptionally low thermal conductivity realized in the chalcopyrite CuFeS2 via atomic-level lattice engineering
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通过原子级晶格工程在黄铜矿 CuFeS2 中实现极低的热导率
DOI：
10.1016/j.nanoen.2022.106941
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发表时间：
2022-01-16
期刊：
影响因子：
17.6
通讯作者：
Chung, In
中科院分区：
文献类型：
--
作者：
Ge, Bangzhi;Lee, Hyungseok;Chung, In
在固体晶格中设计不规则但理想的原子排列可以极大地改变其固有的物理性质，超出了普通掺杂和合金化的预期。然而，固体的结构通常是由固态反应中的热力学偏好决定的，这严格限制了精细的原子级晶格工程。在这里，我们报告了一种以高度可预测的方式实现理想缺陷结构的新策略，以控制固体的热和电荷输运性质。在四方黄铜矿CuFeS2中引入异常高浓度的铟，形成Cu1-xInxFeS2 （x = 0-0.12）体系，稳定了周围基体中异常的局部结构，即立方锌闪锌矿结构的高温多晶和Cu+亚晶格中5(2)个孤对电子置换的in +阳离子。通过载热声子的多尺度散射和软化机制，这极大地抑制了四面体网络CuFeS2众所周知的高晶格热导率，使其在723 K时降至创纪录的低值-0.79 W m(-1) K-1，接近其理论下限。因此，在黄铜矿硫化物中获得了最高的热电值ZT。我们的设计原理利用了组成元素的标准电位和离子半径，因此很容易适用于设计各种类型的固体。值得注意的是，我们利用扫描透射电子显微镜从理想位置直接成像了稳定高温相和离心In+的位置无序的原子级结构。这一观察结果显示了我们的材料设计策略是如何工作的，并为在晶格中引入相容或不相容原子时固体中的局部结构是如何形成提供了重要的理解。
Designing irregular but desirable atomic arrangements in crystal lattices of solids can greatly change their intrinsic physical properties beyond expectations from common doping and alloying. However, structures of solids are generally determined by thermodynamic preferences during solid-state reactions, strictly restricting delicate atomic-level lattice engineering. Here, we report a new strategy of realizing desirable defect architecture in a highly predictable way to control thermal and charge transport properties of solids. Introducing unusually high concentration indium to the tetragonal chalcopyrite CuFeS2 to form the Cu1-xInxFeS2 (x = 0-0.12) system stabilizes the highly unusual local structure, namely, high-temperature polymorph of cubic zinc blende structure in the surrounding matrix and displaced In+ cation with 5s(2) lone pair electrons from the Cu+ sublattice. This substantially suppresses notoriously high lattice thermal conductivity of tetrahedrally networked CuFeS2 to record-low values -0.79 W m(-1) K-1 at 723 K through multiscale scattering and softening mechanisms of heat carrying phonon, approaching its theoretical lower limit. Consequently, one of the highest thermoelectric figures of merit, ZT, among chalcopyrite sulfides is achieved. Our design principle utilizes standard potentials and ionic radius of constituent elements, thereby readily applicable to designing various classes of solids. Remarkably, we directly imaged the atomic-level structure of positional disorder stabilizing the high-temperature phase and off-centered In+ from the ideal position employing a scanning transmission electron microscope. This observation shows how our material design strategy works, and provides important understanding for how local structures in solids form when either compatible or incompatible atoms are introduced to the crystal lattices.