The composition dependencies of crystal structure, and electrical and electromechanical properties were systematically investigated for epitaxial films of (1−x)(Bi0.5Na0.5)TiO3–x(Bi0.5K0.5)TiO3 [(1−x)BNT–xBKT (x = 0 –1)] deposited on (100) c SrRuO3//(100)SrTiO3 substrates by a hydrothermal method. An In-plane crystal lattice was clamped by that of underlying SrRuO3 irrespective of the x value. The dielectric constant decreased monotonously with increasing x. The polarization–electric field hysteresis loops were imprinted due to the preferential polarization in the films. In addition, the increase of tetragonality with increasing x value contributes to the increase of saturation and remnant polarization (P sat. and P r, respectively), coercive field (E c) as well as P r/P sat. values. The effective piezoelectric coefficient (near E = 0 kV cm−1) improved considerably with increasing x, reaching a maximum of 62 pm V−1 in the BKT film. A comprehensive and systematic study has been performed on (1−x)BNT–xBKT epitaxial films in this work, which lays the foundation for further research of this system in the future.

中文翻译：

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水热法生长的外延(1-x)(Bi0.5Na0.5)TiO3-x(Bi0.5K0.5)TiO3薄膜的晶体结构、铁电和压电性能

系统地研究了 (1-x)(Bi0.5Na0.5)TiO3-x(Bi0.5K0.5)TiO3 [(1-x)BNT- xBKT (x = 0 –1)] 通过水热法沉积在 (100) c SrRuO3//(100)SrTiO3 基材上。无论 x 值如何，面内晶格都被下面的 SrRuO3 的晶格夹住。介电常数随着 x 的增加而单调下降。由于薄膜中的优先极化，极化 - 电场滞后回线被压印。此外，随着 x 值的增加，四方性的增加有助于饱和和剩余极化（分别为 P sat. 和 P r）、矫顽场（E c ）以及 P r / P sat 的增加。值。有效压电系数（接近 E = 0 kV cm-1）随着 x 的增加而显着提高，在 BKT 膜中达到最大值 62 pm V-1。本工作对(1-x)BNT-xBKT外延薄膜进行了全面系统的研究，为今后对该体系的进一步研究奠定了基础。