A material catalogue with glass-like thermal conductivity mediated by crystallographic occupancy for thermoelectric application,Energy & Environmental Science

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A material catalogue with glass-like thermal conductivity mediated by crystallographic occupancy for thermoelectric application
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2021-4-21 , DOI: 10.1039/d1ee00738f
Zihang Liu _{1,

2,

3,

4} , Wenhao Zhang _{1,

2,

3,

4,

5} , Weihong Gao _{1,

2,

3,

4} , Takao Mori _{1,

2,

3,

4,

5}

Affiliation

Discovering materials with intrinsically low lattice thermal conductivity κ_lat is an important route for achieving high thermoelectric performance. In reality, the conventional synthetic approach, however, relies on trial and error. Herein, we proposed a new crystallographic parameter, namely the site occupancy factor, as an effective indicator to identify a material catalogue with low κ_lat. Taking Cu₆Te₃S, in which some Cu atoms show partial occupancy, as the representative sample, it was found that this compound exhibited ultralow κ_lat with weak temperature dependence from 5 K to 350 K. The appearance of a boson peak and unusual two-level tunneling states in the heat capacity measurement revealed the low-lying optical modes and dynamic diffusion disorder, respectively. This glass-like thermal property in a crystalline material arose from the combination of the anharmonic and anisotropic vibration of the Cu atom, the ionic bond feature around the Cu atom, and the global weak bonding, confirmed by the calculated phonon dispersion, electron localization function, and potential energy curves. Utilizing the proposed indicator of partial occupancy, we searched in the Crystallography Open Database for further potential candidate materials with low κ_lat. As a further test of the efficacy of this strategy, two unearthed compounds were synthesized and both were indeed found to exhibit very low κ_lat, around 0.6 W m⁻¹ K⁻¹ at 300 K. Our work explored the close relationship between crystallography and thermal property in crystalline materials and revealed the impact of partial occupancy in complex lattice dynamics, opening up new avenues towards discovering materials with low κ_lat.

中文翻译：

由晶体占有率介导的具有玻璃状导热性的材料目录，用于热电应用

发现材料有固有的低晶格热导率κ _LAT是达到较高的热电性能的重要途径。然而，实际上，常规的合成方法依赖于反复试验。在此，我们提出了一个新的晶体参数，即占位因素，作为一种有效的指标来识别材料目录与低κ_纬度。取的Cu ₆碲₃ S，在其中一些Cu原子表现出部分占用，作为代表抽样，我们发现，这种化合物显示超低κ _LAT在5 K至350 K的温度范围内具有较弱的温度依赖性。在热容测量中出现玻色子峰和不寻常的两级隧穿态分别揭示了低层光学模式和动态扩散无序。晶体材料中的这种玻璃状热性质是由Cu原子的非谐振动和各向异性振动，Cu原子周围的离子键特征以及整体弱键共同产生的，该结果由计算出的声子色散，电子局部化函数确定和势能曲线。利用部分占据的建议指标，我们搜查了晶体开放式数据库与低进一步的潜在候选材料κ _LAT。作为该策略的有效性的进一步的试验中，两个出土合成化合物和两者都确实发现表现出非常低的κ _LAT，周围为0.6W米^-1 ķ ^-1在300K我们的工作探索晶体学和之间的密切关系在结晶材料的热性质和揭示部分占据在复杂晶格动力学的影响，朝向与发现低材料开辟了新的途径κ_纬度。

更新日期：2021-05-13

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