Considering finite size effect, ferroelectric nanowires may show novel phenomena compared to ferroelectric thin film and bulk. Here we investigated the effect of width and surface compressive stress on electrocaloric cooling in ferroelectric nanowire by using thermodynamic calculations and phase-field simulations. It was found that the isothermal entropy change and adiabatic temperature change in nanowire are 50% larger than that in thin film due to different mechanical boundary conditions of nanowire and thin film. The largest electrocaloric temperature changes were shown to increase significantly either with the decrease in nanowire width or the increase with the surface compressive stress. It was also revealed that the largest intrinsic entropy changes are almost the same for different nanowires with different widths and various stresses. The present study therefore contributes to the understanding of size effects of electrocaloric cooling and provides guidance for experiments to design high-efficiency cooling devices using ferroelectric nanosystems.

中文翻译：

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铁电纳米线中电热冷却的尺寸效应

考虑到有限尺寸效应，与铁电薄膜和块体相比，铁电纳米线可能会显示出新颖的现象。在这里，我们通过使用热力学计算和相场模拟研究了宽度和表面压缩应力对铁电纳米线电热冷却的影响。发现由于纳米线和薄膜的机械边界条件不同，纳米线的等温熵变和绝热温度变化比薄膜的等温熵变和绝热温度变化大50％。最大的电热温度变化显示出随着纳米线宽度的减小或表面压应力的增加而显着增加。还揭示出，对于具有不同宽度和不同应力的不同纳米线，最大的内在熵变化几乎相同。