Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic and Information Engineering , Xi'an Jiaotong University , Xi'an 710049 , China.
Department of Chemistry and 4D LABS , Simon Fraser University , Burnaby , British Columbia V5A 1S6 , Canada.
ACS Appl Mater Interfaces. 2018 Jul 18;10(28):23945-23951. doi: 10.1021/acsami.8b02239. Epub 2018 Jul 3.
The BiNaTiO-based ferroelectric is one of the most promising candidates for environment-friendly lead-free ferroelectric/piezoelectric materials for various applications such as actuators and micro-electromechanical systems. The understanding and tailoring of the ferro-(piezo-)electric properties of thin films, however, are strongly hindered by the formation of the defects such as dislocations, ion vacancies in the film, as well as by the complexity of the interface between the film and the substrate. An ideal system for the study of the polarization behavior in the ferro-(piezo-)electric film would be a fully matched system. In this work, monocrystalline 0.89BiNaTiO-0.11BaTiO thin films were epitaxially grown on (001)-oriented Nb-doped SrTiO substrates using a sol-gel technique. The films were almost fully lattice- and thermally matched with the substrate, thus avoiding the impact of dislocations and thermal stress. The films were self-poled by a built-in electric field, originating from the sedimentation of heavier atoms during the film preparation. As a consequence, an upward self-polarization was introduced into the films, giving rise to asymmetric phase hysteresis loops and domain switching current responses. These results highlight the importance of the interface complexity for the self-polarization of piezoelectric thin films, even for fully matched films, which will therefore facilitate the control of properties of piezoelectric films and their applications for various functional devices.
基于 BiNaTiO 的铁电体是最有前途的无铅铁电/压电材料之一，可用于各种应用，如执行器和微机电系统。然而，薄膜的铁电（压）电性能的理解和调整受到诸如位错、薄膜中的离子空位等缺陷的形成以及薄膜与衬底之间界面的复杂性的强烈阻碍。用于研究铁电（压）电薄膜中极化行为的理想体系是完全匹配的体系。在这项工作中，使用溶胶-凝胶技术在（001）取向的掺铌 SrTiO 衬底上外延生长了单晶 0.89BiNaTiO-0.11BaTiO 薄膜。这些薄膜几乎与衬底完全晶格和热匹配，从而避免了位错和热应力的影响。这些薄膜通过内置电场自极化，这是由于在薄膜制备过程中较重原子的沉降而产生的。结果，引入了向上的自极化，导致不对称的相滞后回线和畴切换电流响应。这些结果强调了界面复杂性对压电薄膜自极化的重要性，即使对于完全匹配的薄膜也是如此，这将有助于控制压电薄膜的性能及其在各种功能器件中的应用。
