Origin of thermally stable ferroelectricity in a porous barium titanate thin film synthesized through block copolymer templating
Origin of thermally stable ferroelectricity in a porous barium titanate thin film synthesized through block copolymer templating
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DOI：
10.1063/1.4995650
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发表时间：
2017-07-01
期刊：
影响因子：
6.1
通讯作者：
Hossain, Md. Shahriar A.
中科院分区：
文献类型：
--
作者：
Suzuki, Norihiro;Osada, Minoru;Hossain, Md. Shahriar A.
以两亲性嵌段共聚物胶束为结构导向剂，采用表面活性剂辅助的溶胶-凝胶法制备了多孔钛酸钡（BaTiO 3）薄膜。在多孔BaTiO 3薄膜的拉曼光谱中，在约710 cm（-1）处观察到对应于铁电性四方相的峰，并且其在比体单晶BaTiO 3的居里温度（类似于130 ℃）高得多的温度下保持稳定。测量结果表明，BaTiO 3薄膜的铁电性具有很高的热稳定性。通过分析高分辨率透射电子显微镜图像的钛酸钡薄膜的快速傅里叶变换映射方法，在钛酸钡框架的应力的空间分布被清楚地可视化。仔细分析还表明，BaTiO 3薄膜中的孔隙率引入了各向异性压应力，该压应力使晶体变形。所得到的伸长的晶胞引起Ti 4+阳离子从晶格中心的进一步位移。这种位移增加了钛酸钡薄膜的电偶极矩，有效地提高了其铁（压电）电。(C)2017年作者。
A porous barium titanate (BaTiO3) thin film was chemically synthesized using a surfactant-assisted sol-gel method in which micelles of amphipathic diblock copolymers served as structure-directing agents. In the Raman spectrum of the porous BaTiO3 thin film, a peak corresponding to the ferroelectric tetragonal phase was observed at around 710 cm(-1), and it remained stable at much higher temperature than the Curie temperature of bulk single-crystal BaTiO3 (similar to 130 degrees C). Measurements revealed that the ferroelectricity of the BaTiO3 thin film has high thermal stability. By analyzing high-resolution transmission electron microscope images of the BaTiO3 thin film by the fast Fourier transform mapping method, the spatial distribution of stress in the BaTiO3 framework was clearly visualized. Careful analysis also indicated that the porosity in the BaTiO3 thin film introduced anisotropic compressive stress, which deformed the crystals. The resulting elongated unit cell caused further displacement of the Ti4+ cation from the center of the lattice. This displacement increased the electric dipole moment of the BaTiO3 thin film, effectively enhancing its ferro(piezo) electricity. (C) 2017 Author(s).