Abstract Fundamental material parameters governing the carrier transport in thermoelectric materials are affected by microstructural characteristics. We have investigated the effects of compaction duration on microstructure and the thermoelectric properties of Sb doped Mg2Si0.4Sn0.6. The transport properties show drastic changes with increasing compaction duration from 10 min to 40 min. A TEM-EDS analysis on samples sintered for 20 min and 40 min highlights Mg depleted grain boundaries and local compositional inhomogeneities but gives no indications for dopant loss. The transport properties were analyzed using a single parabolic band (SPB) model, and the observed changes can be attributed to carrier (n) loss, diminished carrier mobility (μ0) and a reduction in lattice thermal conductivity (κlat). Comparatively stronger carrier scattering in longer sintered sample is a combined effect of increasing electron-phonon interaction (higher EDef) and local compositional inhomogeneities in the material which are both linked to Mg depletion. The transport behavior of these samples can be fully captured by the SPB model only after the addition of grain boundary scattering in conjunction to acoustic phonon and alloy scattering. Furthermore, compensation between a lower κlat and μ0 of the longer sintered sample led to a similar z T m a x = 1.3 ± 0.18 and an only marginally reduced performance parameter β. While it is evident that Mg deficiency modifies the transport properties, the thermoelectric performance is only mildly affected and a Mg2(Si,Sn) based TE device can therefore withstand some Mg loss without a deterioration of its performance.

中文翻译：

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分析 n 型 Mg2Si0.4Sn0.6 中的热电传输及其与微观结构效应的相关性：对 Mg 作用的洞察

摘要 控制热电材料中载流子传输的基本材料参数受微观结构特征的影响。我们研究了压实持续时间对 Sb 掺杂的 Mg2Si0.4Sn0.6 的微观结构和热电性能的影响。随着压实持续时间从 10 分钟增加到 40 分钟，传输特性显示出剧烈的变化。对烧结 20 分钟和 40 分钟的样品进行的 TEM-EDS 分析突出显示了 Mg 耗尽的晶界和局部成分不均匀性，但没有给出掺杂剂损失的迹象。使用单抛物线带 (SPB) 模型分析传输特性，观察到的变化可归因于载流子 (n) 损失、载流子迁移率降低 (μ0) 和晶格热导率 (κlat) 降低。较长烧结样品中相对较强的载流子散射是电子-声子相互作用增加（更高 EDef）和材料中局部成分不均匀性的综合效应，这两者都与镁耗尽有关。只有在添加晶界散射与声子和合金散射相结合后，SPB 模型才能完全捕获这些样品的传输行为。此外，较长烧结样品的较低 κlat 和 μ0 之间的补偿导致类似的 z T max = 1.3 ± 0.18 和仅略微降低的性能参数 β。虽然很明显 Mg 缺乏会改变传输特性，但热电性能仅受到轻微影响，因此基于 Mg2(Si,Sn) 的 TE 器件可以承受一些 Mg 损失而不会降低其性能。