Kim Yoon-Hyun, Dong Lei, Osada Minoru, Li Bao-Wen, Ebina Yasuo, Sasaki Takayoshi
International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan. Grduate School of Advanced Science and Engineering, Waseda University, Shinjyu-ku, Tokyo 169-8555, Japan.
Nanotechnology. 2015 Jun 19;26(24):244001. doi: 10.1088/0957-4484/26/24/244001. Epub 2015 May 27.
Control over the emergence of ferroelectric order remains a fundamental challenge for the rational design of artificial materials with novel properties. Here we report a new strategy for artificial design of layered perovskite ferroelectrics by using oxide nanosheets (high-k dielectric Ca2Nb3O10 and insulating Ti0.87O2) as a building block. We approached the preparation of superlattice films by a layer-by-layer assembly involving Langmuir-Blodgett deposition. The artificially fabricated (Ti0.87O2/Ca2Nb3O10)2(Ti0.87O2) superlattices are structurally unique, which is not feasible to create in the bulk form. By such an artificial structuring, we found that (Ti0.87O2/Ca2Nb3O10)2(Ti0.87O2) superlattices possess a new form of interface coupling, which gives rise to ferroelectricity with a good fatigue-free characteristic. Considering the flexibility of self-assembled nanosheet interfaces, this technique provides a route to synthesize a new kind of layered ferroelectric oxides.
对于具有新颖特性的人工材料的合理设计而言，控制铁电有序的出现仍然是一项根本性挑战。在此，我们报道一种通过使用氧化物纳米片（高介电常数的Ca2Nb3O10和绝缘的Ti0.87O2）作为构建单元来人工设计层状钙钛矿铁电体的新策略。我们通过涉及朗缪尔-布洛杰特沉积的逐层组装方法来制备超晶格薄膜。人工制备的(Ti0.87O2/Ca2Nb3O10)2(Ti0.87O2)超晶格在结构上具有独特性，这在块状形式中是无法实现的。通过这种人工构造，我们发现(Ti0.87O2/Ca2Nb3O10)2(Ti0.87O2)超晶格具有一种新的界面耦合形式，这种耦合会产生具有良好抗疲劳特性的铁电性。考虑到自组装纳米片界面的灵活性，该技术为合成新型层状铁电氧化物提供了一条途径。
