Origin of thermally stable ferroelectricity in a porous barium titanate thin film synthesized through block copolymer templating

Norihiro Suzuki, Minoru Osada, Motasim Billah, Zeid Abdullah Alothman, Yoshio Bando, Yusuke Yamauchi, Md Shahriar A. Hossain

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    Abstract

    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 (∼130 °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.

    Original languageEnglish
    Article number076111
    JournalAPL Materials
    Volume5
    Issue number7
    DOIs
    Publication statusPublished - 2017 Jul 1

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    ASJC Scopus subject areas

    • Materials Science(all)
    • Engineering(all)

    Cite this

    Suzuki, N., Osada, M., Billah, M., Alothman, Z. A., Bando, Y., Yamauchi, Y., & Hossain, M. S. A. (2017). Origin of thermally stable ferroelectricity in a porous barium titanate thin film synthesized through block copolymer templating. APL Materials, 5(7), [076111]. https://doi.org/10.1063/1.4995650