Department of Materials Science and Engineering, Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, China.
Nat Commun. 2016 Dec 19;7:13807. doi: 10.1038/ncomms13807.
The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50-80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials.
弛豫铁电固溶单晶中超高压电性的发现是铁电材料的一个突破。弛豫铁电固溶体的一个关键特征是存在极性纳米区域，这是一种纳米尺度的非均匀性，与正常铁电畴共存。尽管经过了二十年的广泛研究，但极性纳米区域对弛豫铁电体基础压电性能的贡献尚未确定。在这里，我们使用低温实验和相场模拟相结合的方法，定量表征了极性纳米区域对弛豫铁电晶体介电/压电响应的贡献。极性纳米区域对室温介电和压电性能的贡献在 50-80%之间。提出了一种介观机制来揭示弛豫铁电体中高压电性的起源，其中铁电基体中取向一致的极性纳米区域可以促进极化旋转。该机制强调了局部结构对铁电材料宏观性能的关键作用。
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