Thermal stability of self-polarization in a (K,Na)NbO3film prepared by the hydrothermal method

Akinori Tateyama, Yoshiharu Ito, Takahisa Shiraishi, Yuichiro Orino, Minoru Kurosawa, Hiroshi Funakubo

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Herein, the systematic change in the self-polarization behavior against the post-heat treatment after film deposition was investigated to understand the origin of self-polarization in hydrothermally prepared (K x Na1-x )NbO3 films with x = 0.88 at 240 C below the Curie temperature. The transverse piezoelectric constant, e 31,f , was evaluated by the cantilever method. The as-prepared films and heat-treated films at 300 C had an almost perfectly self-polarized state and showed e 31,f of ∼-5.0 C m-2 without applying an electric field as a poling treatment. Also, the piezoelectric response shows good linearity with the asymmetric piezoelectric butterfly curves, showing imprint characteristics. The self-polarized states were maintained until the heat treatment above the Curie temperature. Moreover, the self-polarized film was successfully deposited on the post-heat-treated film without the self-polarized state. This result suggests that the self-polarized state is generated regardless of the polarized state of the underlying layer by the hydrothermal synthesis in which deposition temperature is below the Curie temperature.

Original languageEnglish
Article numberSFFB03
JournalJapanese Journal of Applied Physics
Publication statusPublished - Nov 2021
Externally publishedYes


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