压电材料中相共存态与其性能的关系

由于铅元素有毒，研究人员正努力寻找高性能无铅压电材料以便取代含铅压电材料，因此如何开发高性能压电材料的机制就变得极为重要。此文利用6阶朗道-德文希尔模型计算了不同相共存态的自由能表达（包括单相，两相，三相以及四相共存）。通过计算结果发现，不同的相共存态对应不同的自发极化伸缩或者偏转的能垒：铁电相共存越多，则极化偏转能垒越低，而与顺电相共存，则可以极大地降低极化伸缩能垒，不同的能垒也导致了对材料压电介电性能不同的增强能力。同时，不同相共存点的实验结果也证明了这一发现。研究澄清了相共存态与其对性能增强能力的关系，而且重新将极化伸缩和偏转机制（自由能观点）转变成了更简单的相共存态机理（材料结构观点），从而为寻找和制备高性能压电材料提供了一种更快捷的方式。

Relationship between Phase Coexistence and Properties in Piezoelectric M aterials

Due to the toxicity of Pb, researchers are searching for high performance Pb free pi-ezoelectrics to substitute for the Pb based ones, and the mechanism for developing high perform-ance piezoelectrics are essentially needed.In this paper, we used a 6th order Landau-Devon-shire model to calculate the free energy for different phase coexistence situations （ single phase, two phases, three phases and four phases） .Results showed that different phase coexistence sta-tuses corresponded to different energy barriers for polarization rotation and extension： coexisted with more ferroelectric phases, the polarization rotation barrier will be lower, and coexisted with paraelectric phases, the polarization extension barrier will be extremely reduced, and different energy barriers result in different enhancement abilities for materials′piezoelectricity and permit-tivity.Experimental proofs were also provided to verify this finding .Our study clarifies the rela-tionship between phase coexistence states with its properties performance , and re-interprets po-larization rotation and extension mechanism （ a free energy view） into a simple phase coexistence scenario （ a material structure view） , which may offer a fast way to find and engineer high performance piezoelectrics .