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arXiv 2103.16919cond-mat.mtrl-sci
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SrTiO3晶界电荷输运的调制:室温下高热电功率因数

Modulation of Charge Transport at Grain Boundaries in SrTiO3: Toward a High Thermoelectric Power Factor at Room Temperature

Jianyun Cao, Dursun Ekren, Yudong Peng, Feridoon Azough, Ian A. Kinloch, Robert Freer

摘要:

为了在低温下实现高性能,具有热激活电导率的热电材料中的晶界性质的调制是至关重要的。在这项工作中,我们直接表明,在钙钛矿SrTiO 3中的晶界处的势垒的调制改变了块体材料的电导率的低温依赖性。通过在增加强度的还原环境中烧结样品,我们生产了La0.08Sr0.9TiO3(LSTO)陶瓷,逐渐改变其导电行为从热激活单晶样,只有微小的变化塞贝克系数。Kelvin探针力显微镜的表面电位成像发现,在更还原的环境中处理过的LSTO样品中,晶界处的势垒较低。一个理论模型,使用带偏移在晶界上表示的势垒同意与测量的电导率的晶界电位依赖性。目前的工作表明,在330 K的电导率(从85到1287 S cm-1)和功率因数(从143到1745 μW m-1 K-2)的数量级的提高,通过这种调制的电荷传输在晶界。这种显着减少晶界上的电荷传输SrTiO 3的影响提供了一个机会,以实现最终的“声子玻璃电子晶体”通过适当的实验设计和加工。

英文摘要:

Modulation of the grain boundary properties in thermoelectric materials that have thermally activated electrical conductivity is crucial in order to achieve high performance at low temperatures. In this work, we show directly that the modulation of the potential barrier at the grain boundaries in perovskite SrTiO3 changes the low-temperature dependency of the bulk material's electrical conductivity. By sintering samples in a reducing environment of increasing strength, we produced La0.08Sr0.9TiO3 (LSTO) ceramics that gradually change their electrical conductivity behavior from thermally activated to single-crystal-like, with only minor variations in the Seebeck coefficient. Imaging of the surface potential by Kelvin probe force microscopy found lower potential barriers at the grain boundaries in the LSTO samples that had been processed in the more reducing environments. A theoretical model using the band offset at the grain boundary to represent the potential barrier agreed well with the measured grain boundary potential dependency of conductivity. The present work showed an order of magnitude enhancement in electrical conductivity (from 85 to 1287 S cm-1) and power factor (from 143 to 1745 μW m-1 K-2) at 330 K by this modulation of charge transport at grain boundaries. This significant reduction in the impact of grain boundaries on charge transport in SrTiO3 provides an opportunity to achieve the ultimate 'phonon glass electron crystal' by appropriate experimental design and processing.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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