Large electrocaloric effect in lead-free ferroelectric Ba0.85Ca0.15Ti0.9Zr0.1O3 thin film heterostructure
Large electrocaloric effect in lead-free ferroelectric Ba0.85Ca0.15Ti0.9Zr0.1O3 thin film heterostructure
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DOI：
10.1063/5.0039143
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发表时间：
2021-02
期刊：
影响因子：
6.1
通讯作者：
A. Barman;Subhashree Chatterjee;Canlin Ou;Yau Yau Tse-Yau;N. Banerjee;S. Kar‐Narayan;A. Datta;D. Mu
中科院分区：
文献类型：
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作者：
A. Barman;Subhashree Chatterjee;Canlin Ou;Yau Yau Tse-Yau;N. Banerjee;S. Kar‐Narayan;A. Datta;D. Mu
据报道，由近室温电结构相变驱动的应变工程 Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) 薄膜异质结构具有大的电热效应。使用脉冲激光沉积在单晶 SrTiO3 (100) 基板上生长外延 BCZT/La0.7Sr0.3MnO3 (BCZT/LSMO) 异质结构。深入的 X 射线衍射和 X 射线光谱分析揭示了异质结构的单晶性质和化学计量生长。温度相关的 X 射线衍射和介电测量都揭示了 BCZT/LSMO 异质结构中 430 K 附近广泛的二级相变。通过对实验数据的详细理论分析，证实了 430 K 左右的相变本质上是二阶相变，这与在块体 BCZT 材料中观察到的一阶相变不同。极化的热力学分析表明，在 1000 kV cm−1 的场变化下，430 K 时绝热温度变化达到前所未有的 13.5 K，这是迄今为止在无铅材料中未观察到的。在较宽的工作温度范围（330 K < T < 480 K）内，极宽的绝热温度变化 ΔT(T) 曲线导致相对冷却能力增强，高于迄今为止大多数电热材料报道的冷却能力。我们提出，界面应变引起的 BCZT 层四方变形增强，在 BCZT/LSMO 异质结构系统中产生了这些大的电热效应。无铅 BCZT 薄膜中大电热效应的展示可能为环保固态冷却应用的人造异质结构设计开辟新途径。
A large electrocaloric effect is reported in a strain-engineered Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) thin film heterostructure driven by the near room-temperature electro-structural phase transition. An epitaxial BCZT/La0.7Sr0.3MnO3 (BCZT/LSMO) heterostructure was grown on a single-crystal SrTiO3 (100) substrate using pulsed laser deposition. In-depth x-ray diffraction and x-ray spectroscopic analyses revealed the single-crystalline nature and stoichiometric growth of the heterostructure. Both temperature dependent x-ray diffraction and dielectric measurements revealed a broad second-order-type phase transition near 430 K in the BCZT/LSMO heterostructure. From detailed theoretical analyses of the experimental data, it was confirmed that the phase transition around 430 K is second-order in nature, unlike the first-order transition observed in bulk BCZT materials. Thermodynamic analyses of polarization revealed an unprecedently large adiabatic temperature change of 13.5 K at 430 K under a field change of 1000 kV cm−1, hitherto unobserved in a lead-free material. Extremely broad adiabatic temperature change ΔT(T) curves over a wide working range of temperatures (330 K < T < 480 K) resulted in enhanced relative cooling powers, which are higher than those reported so far in most electrocaloric materials. We propose that an interfacial strain-induced enhanced tetragonal distortion of the BCZT layer gives rise to these large electrocaloric effects in the BCZT/LSMO heterostructure system. The demonstration of a large electrocaloric effect in the lead-free BCZT thin film may open up new pathways toward the design of artificial heterostructures for eco-friendly solid-state cooling applications.