热电材料
非谐性
化学
热电效应
声子
离域电子
各向异性
功勋
声子散射
凝聚态物理
电子能带结构
带隙
热导率
密度泛函理论
计算化学
光电子学
材料科学
热力学
物理
量子力学
有机化学
复合材料
作者
Jialin Ji,Qinghang Tang,Mingjia Yao,He Yang,Yeqing Jin,Yubo Zhang,Jinyang Xi,David J. Singh,Jiong Yang,Wenqing Zhang
摘要
We demonstrate the use of functional-unit-based material design for thermoelectrics. This is an efficient approach for identifying high-performance thermoelectric materials, based on the use of combinations of functional fragments relevant to desired properties. Here, we reveal that linear triatomic resonant bonds (LTRBs) found in some Zintl compounds provide strong anisotropy both structurally and electronically, along with strong anharmonic phonon scattering. An LTRB is thus introduced as a functional unit, and compounds are then screened as potential thermoelectric materials. We identify 17 semiconducting candidates from the MatHub-3d database that contain LTRBs. Detailed transport calculations demonstrate that the LTRB-containing compounds not only have considerably lower lattice thermal conductivities than other compounds with similar average atomic masses, but also exhibit remarkable band anisotropy near the valence band maximums due to the LTRB. K5CuSb2 is adopted as an example to elucidate the fundamental correlation between the LTRB and thermoelectric properties. The [Sb-Cu-Sb]5- resonant structures demonstrate the delocalized Sb-Sb interaction within each LTRB, resulting in the softening of TA phonons and leading to large anharmonicity. The low lattice thermal conductivity (0.39 W/m·K at 300 K) combined with the band anisotropy results in a high thermoelectric figure of merit (ZT) for K5CuSb2 of 1.3 at 800 K. This work is a case study of the functional-unit-based material design for the development of novel thermoelectric materials.
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