The electrocaloric effect, that is, the temperature change experienced by an insulator upon application of an electric field, offers promising ecofriendly alternatives to refrigeration. However, the theoretical treatments of this response are mostly case specific and lack a unified picture revealing the similarities and differences among the various known effects. Here, we show that the electrocaloric effect lends itself to a straightforward interpretation when expressed as a Taylor series in the external field. Our formalism explains in a unified and simple way the most notable small-field effects reported in the literature, namely the so-called normal and inverse electrocaloric responses, corresponding to an increase or decrease of temperature under applied field, as usually found in ferroelectrics or antiferroelectrics, respectively. This helps us to clarify their physical interpretation. We then discuss in detail atomistic simulations for the prototype ferroelectric PbTiO₃, explicitly evaluating subtle predictions of the theory, such as the occurrence of competing contributions to the electrocaloric response.

电热效应，即绝缘体在施加电场时所经历的温度变化，为制冷提供了有前景的环保替代品。然而，对这种反应的理论处理大多是针对具体情况的，缺乏揭示各种已知效应之间异同的统一图景。在这里，我们表明，当在外部场中表示为泰勒级数时，电热效应有助于直接解释。我们的形式主义以统一和简单的方式解释了文献中报道的最显着的小场效应，即所谓的正常和逆电热响应，对应于外加场下温度的升高或降低，通常在铁电体或反铁电体，分别。这有助于我们澄清它们的物理解释。然后我们详细讨论原型铁电 PbTiO 的原子模拟₃，明确评估该理论的微妙预测，例如对电热响应的竞争贡献的发生。