npj Computational Materials

A thermodynamic potential for barium zirconate titanate solid solutions（锆钛酸钡固溶体的热力学势）
Jinlin Peng, Dongliang Shan, Yunya Liu, Kai Pan, Chihou Lei, Ningbo He, Zhenyu Zhang & Qiong Yang
npj Computational Materials 4:66 (2018)
doi:s41524-018-0126-3
Published online:30 November 2018
Abstract| Full Text | PDF OPEN

摘要:作为一种无铅铁电材料，锆钛酸钡[Ba(ZrxTi1？x)O3]固溶体具有很大的应用潜力，已经引起了人们的极大兴趣。基于Landau-Devonshire唯象理论的热力学分析方法，是铁电材料理论研究的有力方法，但由于缺乏相应的热力学势，因而不能应用于 Ba(ZrxTi1？x)O3的研究。本研究首先构建了Ba(ZrxTi1？x)O3（0≤x≤0.3）固溶体的热力学势，然后基于所构建的热力学势进行了锆钛酸钡固溶体的热力学分析。分析结果准确地再现了已知的相结构及其相变温度，且与实验测量的极化、介电和压电常数很好地吻合。研究发现，室温下Ba(ZrxTi1？x)O3固溶体具有三个相界，包括x = 0.013时的四方-正交相界，x = 0.0798时的正交-菱方相界，以及x = 0.2135时的菱方-顺电相界。结果还表明，化学成分诱导的铁电-顺电相界具有优越的机电性能，基于成分诱导的铁电-顺电相界是一种增强Ba(ZrxTi1？x)O3 固溶体机电耦合的新方法。　　

Abstract:Barium zirconate titanate [Ba(ZrxTi1？x)O3] solid solutions are promising lead-free ferroelectric materials that have received substantial interest. Thermodynamic analysis based on phenomenological Landau–Devonshire theory is a powerful method for theoretical investigation of ferroelectric materials, but cannot be applied to Ba(ZrxTi1？x)O3 because there is no thermodynamic potential. In this paper, a thermodynamic potential for Ba(ZrxTi1？x)O3 (0？≤？x？≤？0.3) solid solutions is constructed, and then a thermodynamic analysis carried out. The results accurately reproduce known phase structures and their transition temperatures, with good agreement with experimentally measured polarization, dielectric, and piezoelectric constants. It is found that Ba(ZrxTi1？x)O3 solid solutions at room temperature have three phase boundaries, including a tetragonal–orthorhombic phase boundary at x？=？0.013, an orthorhombic–rhombohedral phase boundary at x？=？0.0798, and a rhombohedral–paraelectric phase boundary at x？=？0.2135. The results also indicate that the chemical composition-induced ferroelectric–paraelectric phase boundary has superior electromechanical properties, suggesting a new way to enhance electromechanical coupling in Ba(ZrxTi1？x)O3 solid solutions.

Editorial Summary

Simulation: thermodynamic potential for solid solutions （模拟：固溶体的热力学势）

本研究构建了锆钛酸钡固溶体的热力学势，并揭示了其在室温下的三个相界。由中国湘潭大学的刘运牙教授领导的合作团队，成功构建了Ba(ZrxTi1-x)O3固溶体的热力学势。他们利用该热力学势进行了热力学分析，再现了与实验结果非常一致的相结构和相变温度。他们发现，Ba(ZrxTi1-x)O3固溶体有三个相界：四方-正交、正交-菱方和菱方-顺电相界。结果表明，化学成分诱导的铁电-顺电相界具有良好的机电性能。他们构建的新热力学势可用来预测锆钛酸钡关联的其他体系的相结构和机电性质。

A thermodynamic potential for barium zirconate titanate solid solutions is constructed and three phase boundaries at room temperature are revealed. A collaborative team led by Yunya Liu from Xiangtan University in China perform theoretical analysis to successfully construct a thermodynamic potential for Ba(ZrxTi1-x)O3 solid solutions. Using this potential, they carry out thermodynamic analysis to reproduce phase structures and transition temperatures that are in good agreement with experiments. They find three phase boundaries for Ba(ZrxTi1？x)O3 solid solutions, including tetragonal-orthorhombic, orthorhombic-rhombohedral and rhombohedral-paraelectric. The results indicate that the chemical composition-induced ferroelectric-paraelectric phase boundaries have good electromechanical properties. The new thermodynamic potential may be applicable to predict phase structures and electromechanical properties in other systems.