Defect modulated dielectric properties in powder aerosol deposited ceramic thick films
Defect modulated dielectric properties in powder aerosol deposited ceramic thick films
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DOI：
10.1016/j.ceramint.2022.07.241
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发表时间：
2022-07
影响因子：
5.2
通讯作者：
Udo Eckstein;N. Khansur;D. Urushihara;T. Asaka;K. Kakimoto;T. Fey;K. Webber
中科院分区：
文献类型：
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作者：
Udo Eckstein;N. Khansur;D. Urushihara;T. Asaka;K. Kakimoto;T. Fey;K. Webber
粉末气溶胶沉积(PAD)陶瓷厚膜在储能和能量收集方面具有广阔的应用前景。室温沉积过程允许在低熔点的衬底上集成陶瓷薄膜，例如不锈钢和聚合物，而不需要烧结。尽管如此，由于内部残余应力、氧缺陷以及与沉积过程相关的纳米晶微结构，其介电和机电性能与大块陶瓷有很大的不同。虽然热退火可以改善薄膜的宏观性能，但需要精确控制薄膜与衬底之间的热膨胀失配，以避免分层和薄膜开裂。在这项研究中，我们提出了一种基于独立衬垫薄膜的制备来确定薄膜的实际热膨胀的方法。利用自支撑薄膜，我们证明了掺杂和工艺条件(如载气种类)直接影响氧缺陷，从而调节氧化膜的单位晶胞体积和电导率。研究发现，这对于在中温环境(500℃)下获得更好的介电性能，保持室温沉积过程的好处至关重要。用透射电子显微镜、扫描电子显微镜和X射线显微层析成像研究了其他致密化机制。
Powder aerosol deposited (PAD) ceramic thick films are a promising candidate for applications in energy storage and energy harvesting. The room-temperature deposition process allows for integration of ceramic films on low-melting substrates, such as stainless steel and polymers, without sintering. Despite this, the dielectric and electromechanical properties vastly differ from bulk ceramics due to internal residual stresses, oxygen defects, and the nano-grained microstructure associated with the deposition process. Although thermal annealing can improve macroscopic properties, precise control of the thermal expansion mismatch between the film and the substrate is required to avoid delamination and film cracking. In this study, we present a method to determine the actual thermal expansion of the film based on the fabrication of freestanding PAD films. Utilizing freestanding films, we demonstrate that dopants and processing conditions such as the carrier gas species directly influence oxygen defects thus modulating the unit cell volume and the conductivity of the oxide film. This is found to be crucial to attain improved dielectric properties within a moderate temperature environment (500 °C) preserving the benefits of the room-temperature deposition process. Additional densification mechanisms are investigated with transmission electron microscopy, scanning electron microscopy, and X-ray microtomography.