Abstract Na0.5+δBi0.5(Ti0.96W0.01Ni0.03)O3 thin films with various Na contents (abbreviated as Na.5+δBTWN, δ = − 3.0, − 1.5, 0, 1.5%) were fabricated on ITO/glass substrates using a chemical–solution process. The effects of Na nonstoichiometry on the microstructure, insulating, ferroelectric and dielectric performances are investigated. The pure perovskite phase can be obtained in Na0.5BTWN and Na0.515BTWN, while for Na0.470BTWN or Na0.485BTWN, the main composition contains secondary phase of TiO2. The grain size increases from 30 nm at δ = − 3.0% to 55 nm at δ = 0%, then decreases to 52 nm with δ = 1.5%. The leakage current of Na0.485BTWN sample is reduced dramatically in comparison with Na0.5+δBTWN (δ = − 3.0, 0, 1.5%). The big recoverable energy–storage density of 63.1 J/cm2 and high energy–storage efficiency of 55.0% can be obtained for Na0.485BTWN due to the improved electric break–down strength and large difference value between the remanent polarization and maximum polarization. Enhanced dielectricity is achieved in Na0.485BTWN with a high tunability of 36.0% and a figure of merit of 4.0 at 450 kV/cm and 500 kHz. These results demonstrated that the crystallization, micrographs and energy storage and dielectric properties of Na0.5Bi0.5TiO3 are highly sensitive to low levels of Na–site nonstoichiometry.

中文翻译：

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化学溶液 NBT 基薄膜的生长、微观结构、储能和介电性能：钠非化学计量的影响

摘要 在 ITO 上制备了不同 Na 含量的 Na0.5+δBi0.5(Ti0.96W0.01Ni0.03)O3 薄膜（缩写为 Na.5+δBTWN, δ = − 3.0, − 1.5, 0, 1.5%） /玻璃基板使用化学溶液工艺。研究了 Na 非化学计量对微观结构、绝缘、铁电和介电性能的影响。在 Na0.5BTWN 和 Na0.515BTWN 中可以获得纯钙钛矿相，而对于 Na0.470BTWN 或 Na0.485BTWN，主要成分为 TiO2 次生相。晶粒尺寸从 δ = - 3.0% 时的 30 nm 增加到 δ = 0% 时的 55 nm，然后减小到 δ = 1.5% 时的 52 nm。与 Na0.5+δBTWN (δ = − 3.0, 0, 1.5%) 相比，Na0.485BTWN 样品的漏电流显着降低。Na0 可获得 63.1 J/cm2 的大可回收储能密度和 55.0% 的高储能效率。485BTWN 由于提高的电击穿强度和剩余极化和最大极化之间的较大差异值。在 Na0.485BTWN 中实现了增强的介电性，在 450 kV/cm 和 500 kHz 下具有 36.0% 的高可调性和 4.0 的品质因数。这些结果表明，Na0.5Bi0.5TiO3 的结晶、显微照片以及能量存储和介电性能对低水平的 Na 位非化学计量高度敏感。