(0 0 l)-oriented Bi₂Sr₂Co₂O_y and Ca₃Co₄O₉ films: Self-assembly orientation and growth mechanism by chemical solution deposition

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• 作者：Xuebin Zhu ; Dongqi Shi ; Shixue Dou ; Yuping Sun ; Qi Li ; Lin Wang ; Wenxian Li ; Weikong Yeoh ; Rongkun Zheng ; Zhixin Chen ; Chunxiu Kong
• 关键词：Self-assembly ; Thermoelectric ; Film ; Chemical solution deposition
• 刊名：Acta Materialia
• 出版年：2010
• 出版时间：July 2010
• 年：2010
• 卷：58
• 期：12
• 页码：4281-4291
• 全文大小：1384 K

文摘

In this study, two typical cobaltate-based thermoelectric films, Bi₂Sr₂Co₂O_y (BSC) and Ca₃Co₄O₉ (CCO), with structures of [Bi₂Sr₂O₄][CoO₂]₂ and [Ca₂CoO₃]^RS[CoO₂], respectively, are prepared by a simple chemical solution deposition on SrTiO₃ (1 0 0), (1 1 0), and (1 1 1) single crystal substrates. X-ray results reveal that all films are c-axis oriented regardless of the orientation of the substrate, suggesting self-assembly orientation. Transmission electron microscopy reveals amorphous/delamination regions for BSC film on SrTiO₃ (1 1 0), and the c-axis stripes of CCO on SrTiO₃ (1 1 1) are inclined at 30° to the interface, whereas the c-axis stripes are parallel to the interfaces for other films. The growth mechanism is established, and the driving force for self-assembly c-axis orientation is attributed to the syneresis stress due to solvent evaporation. The microstructures and properties are also studied and discussed, with the conclusion that self-assembly c-axis oriented layered cobaltates films are good candidates for thermoelectric applications.