Part-crystalline part-liquid state and rattling-like thermal damping in materials with chemical-bond hierarchy
Part-crystalline part-liquid state and rattling-like thermal damping in materials with chemical-bond hierarchy
复制标题
化学键层次材料中的部分结晶部分液态和类响动热阻尼
DOI：
10.1073/pnas.1410349111
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发表时间：
2014-10-21
影响因子：
11.1
通讯作者：
Zhang, Wenqing
中科院分区：
文献类型：
--
作者：
Qiu, Wujie;Xi, Lili;Zhang, Wenqing
了解固体中的热和声子输运在许多学科中都非常重要，例如热电材料，它通常需要极低的晶格热导率（LTC）。通过对填充方钴矿和Cu_3SbSe_3等典型热电化合物的有限温度结构和振动特性的分析，提出了在具有化学键等级的化合物中存在部分结晶部分液态的概念，即某些组分与晶体的其他部分弱键合。这样的材料可以内在地表现出刚性结晶亚晶格和其他波动的非结晶亚晶格的共存，具有热诱导的大振幅振动，甚至是一组物种原子的流动，导致原子级的不均匀性，混合的部分结晶部分液体结构，以及由于类似于非晶材料中玻色子峰的集体软模振动而产生的类似于拨浪鼓的热阻尼。在这些材料中观察到的接近非晶极限的异常LTC只能通过一种有效的方法来描述，该方法近似地将摇铃状阻尼视为“共振”声子散射。
Understanding thermal and phonon transport in solids has been of great importance in many disciplines such as thermoelectric materials, which usually requires an extremely low lattice thermal conductivity (LTC). By analyzing the finite-temperature structural and vibrational characteristics of typical thermoelectric compounds such as filled skutterudites and Cu3SbSe3, we demonstrate a concept of part-crystalline part-liquid state in the compounds with chemicalbond hierarchy, in which certain constituent species weakly bond to other part of the crystal. Such a material could intrinsically manifest the coexistence of rigid crystalline sublattices and other fluctuating noncrystalline sublattices with thermally induced largeamplitude vibrations and even flow of the group of species atoms, leading to atomic-level heterogeneity, mixed part-crystalline partliquid structure, and thus rattling-like thermal damping due to the collective soft-mode vibrations similar to the Boson peak in amorphous materials. The observed abnormal LTC close to the amorphous limit in these materials can only be described by an effective approach that approximately treats the rattling-like damping as a "resonant" phonon scattering.