Suzuki Norihiro, Osada Minoru, Billah Motasim, Bando Yoshio, Yamauchi Yusuke, Hossain Shahriar A
Research Institute for Science and Technology (RIST), Tokyo University of Science (TUS); International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS);
International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS).
J Vis Exp. 2018 Mar 27(133):57441. doi: 10.3791/57441.
Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 °C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications. In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.
钛酸钡（BaTiO₃，以下简称BT）是一种成熟的铁电材料，于20世纪40年代首次被发现，因其铁电性、压电性和介电常数的良好平衡而仍被广泛使用。此外，BT不含任何有毒元素。因此，它被认为是一种环保材料，作为锆钛酸铅（PZT）的替代品引起了相当大的关注。然而，块状BT在约130℃时会失去铁电性，因此，它不能在高温下使用。由于对高温铁电材料的需求不断增长，提高BT中铁电性的热稳定性很重要。在先前的研究中，已经使用了源自异质界面晶格失配的应变。然而，这种方法中的样品制备需要复杂且昂贵的物理过程，这对于实际应用来说是不可取的。在本研究中，我们提出化学合成多孔材料作为引入应变的替代方法。我们使用表面活性剂辅助溶胶 - 凝胶法合成了多孔BT薄膜，其中自组装的两亲性表面活性剂胶束被用作有机模板。通过一系列研究，我们阐明了孔隙的引入对扭曲BT晶格具有与异质界面类似的效果，从而导致铁电性的增强和稳定。由于其简单性和成本效益，这种制造工艺比传统方法具有相当大的优势。
