Complex oxides offer a wide range of functional properties, and recent advances in the fabrication of freestanding membranes of these oxides are adding new mechanical degrees of freedom to this already rich functional ecosystem. Here, photoactuation is demonstrated in freestanding thin film resonators of ferroelectric Barium Titanate (BaTiO₃) and paraelectric Strontium Titanate (SrTiO₃). The free-standing films, transferred onto perforated supports, act as nano-drums, oscillating at their natural resonance frequency when illuminated by a frequency-modulated laser. The light-induced deflections in the ferroelectric BaTiO₃ membranes are two orders of magnitude larger than in the paraelectric SrTiO₃ ones. Time-resolved X-ray micro-diffraction under illumination and temperature-dependent holographic interferometry provide combined evidence for the photostrictive strain in BaTiO₃ originating from a partial screening of ferroelectric polarization by photo-excited carriers, which decreases the tetragonality of the unit cell. These findings showcase the potential of photostrictive freestanding ferroelectric films as wireless actuators operated by light.

中文翻译：

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基于独立式铁电膜的光致伸缩执行器

复杂氧化物提供了广泛的功能特性，而这些氧化物的独立式膜制造的最新进展为这个已经丰富的功能生态系统增加了新的机械自由度。在这里，在铁电钛酸钡 (BaTiO ₃ ) 和顺电钛酸锶 (SrTiO ₃ )的独立式薄膜谐振器中演示了光致动。这些独立的薄膜被转移到穿孔的支撑物上，充当纳米鼓，当被调频激光照射时，以其自然共振频率振荡。铁电 BaTiO ₃膜中的光致偏转比顺电 SrTiO ₃膜中的光致偏转大两个数量级。照明下的时间分辨X射线微衍射和温度相关的全息干涉测量为BaTiO ₃中的光致伸缩应变提供了综合证据，该应变源自光激发载流子对铁电极化的部分屏蔽，这降低了晶胞的四方性。这些发现展示了光致独立式铁电薄膜作为光操作无线致动器的潜力。