Xu Y B, Tang Y L, Zhu Y L, Liu Y, Li S, Zhang S R, Ma X L
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, 110016 Shenyang, China.
Sci Rep. 2016 Oct 11;6:35172. doi: 10.1038/srep35172.
Ferroelectric thin films grown on high index substrates show unusual structural and switching dynamics due to their special strain states. Understanding the misfit relaxation behavior is crucial to facilitate the high index thin film growth with improved quality. In this paper, ferroelectric PbTiO thin films were grown on LaAlO (111) substrates by pulsed laser deposition technique. The microstructures were investigated by combinations of conventional and aberration-corrected transmission electron microscopy. Diffraction contrast analysis and high resolution imaging reveal that high density interfacial dislocations were distributed at the interfaces. These dislocations have mixed character with Burgers vectors of a <110> and line directions of <112>. The edge components of the dislocations, with the Burgers vectors parallel to the interface, accommodate the lattice mismatch and are the main contributor to the misfit relaxation of this system. The formation mechanism of these dislocations is proposed and discussed to elucidate the novel mismatch relaxation behavior of <111> oriented perovskite films.
生长在高指数衬底上的铁电薄膜由于其特殊的应变状态而表现出异常的结构和开关动力学。了解失配弛豫行为对于促进高质量的高指数薄膜生长至关重要。本文采用脉冲激光沉积技术在LaAlO(111)衬底上生长了铁电PbTiO薄膜。通过传统和像差校正透射电子显微镜相结合的方法对微观结构进行了研究。衍射衬度分析和高分辨率成像表明，高密度的界面位错分布在界面处。这些位错具有混合特征，柏氏矢量为a<110>，线方向为<112>。位错的边缘分量，其柏氏矢量平行于界面，适应晶格失配，是该系统失配弛豫的主要贡献者。提出并讨论了这些位错的形成机制，以阐明<111>取向钙钛矿薄膜的新型失配弛豫行为。
