Bridging the macroscopic and atomistic descriptions of the electrocaloric effect.
Bridging the macroscopic and atomistic descriptions of the electrocaloric effect.
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DOI：
10.1103/physrevlett.108.167604
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发表时间：
2012-04
影响因子：
8.6
通讯作者：
I. Ponomareva;S. Lisenkov
中科院分区：
文献类型：
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作者：
I. Ponomareva;S. Lisenkov
采用基于第一性原理的模拟方法对Ba（0.5）Sr（0.5）TiO（3）合金的电热效应进行了模拟。与实验研究类似，我们直接和间接地（通过使用麦克斯韦热力学）模拟这种效应。直接和间接模拟都使用相同的原子框架，使我们能够以系统的方式首次以原子精度对它们进行比较。这种精确的比较，使我们能够提供一个原子和宏观描述的欧洲经委会之间的桥梁，并确定可能严重损害，甚至破坏他们的等价性的因素。我们的计算数据揭示了具有多重铁电转变的铁电体中ECE的内在特征，并证实了这些材料表现出巨大电热响应的潜力。预测了一种材料中负ECE和正ECE的共存以及它们之间不寻常的场驱动转变，在原子水平上解释，并提出了提高电热效率的潜在方法。
First-principles-based simulations are used to simulate the electrocaloric effect (ECE) in Ba(0.5)Sr(0.5)TiO(3) alloys. In analogy with experimental studies we simulate the effect directly and indirectly (via the use of Maxwell thermodynamics). Both direct and indirect simulations utilize the same atomistic framework that allows us to compare them in a systematic way and with an atomistic precision for the very first time. Such precise comparison allows us to provide a bridge between the atomistic and macroscopic descriptions of the ECE and identify the factors that may critically compromise or even destroy their equivalence. Our computational data reveal the intrinsic features of ECE in ferroelectrics with multiple ferroelectric transitions and confirm the potential of these materials to exhibit giant electrocaloric response. The coexistence of negative and positive ECE in one material as well as an unusual field-driven transition between them is predicted, explained at an atomistic level, and proposed as a potential way to enhance the electrocaloric efficiency.