Electrocaloric effects have been experimentally studied in ferroelectrics and incipient ferroelectrics, but not incipient ferroelectrics driven ferroelectric using strain. Here we use optimally oriented interdigitated surface electrodes to investigate extrinsic electrocaloric effects in low-loss epitaxial SrTiO₃ films near the broad second-order 243 K ferroelectric phase transition created by biaxial in-plane coherent tensile strain from DyScO₃ substrates. Our extrinsic electrocaloric effects are an order of magnitude larger than the corresponding effects in bulk SrTiO₃ over a wide range of temperatures including room temperature, and unlike electrocaloric effects associated with first-order transitions they are highly reversible in unipolar applied fields. Additionally, the canonical Landau description for strained SrTiO₃ films works well if we set the low-temperature zero-field polarization along one of the in-plane pseudocubic <100> directions. In future, similar strain engineering could be exploited for other films, multilayers and bulk samples to increase the range of electrocaloric materials for energy efficient cooling.

电热效应已在铁电体和初期铁电体中进行了实验研究，但尚未对使用应变驱动的初期铁电体进行了实验研究。在这里，我们使用最佳取向的叉指表面电极来研究低损耗外延 SrTiO _{3薄膜中的外在电热效应，该薄膜接近由 DyScO 3}基板的双轴面内相干拉伸应变产生的宽二阶 243 K 铁电相变。在包括室温在内的广泛温度范围内，我们的外在电热效应比块体 SrTiO ₃的相应效应大一个数量级，并且与一阶跃迁相关的电热效应不同，它们在单极应用场中具有高度可逆性。此外，如果我们沿面内赝立方 <100> 方向之一设置低温零场偏振，则应变SrTiO ₃薄膜的规范朗道描述效果很好。未来，类似的应变工程可以用于其他薄膜、多层和大块样品，以扩大用于节能冷却的电热材料的范围。