A thermodynamic potential for barium zirconate titanate solid solutions

• Published in: npj computational materials Vol. 4; no. 1; pp. 1 - 9
• Main Authors: Peng, Jinlin, Shan, Dongliang, Liu, Yunya, Pan, Kai, Lei, Chihou, He, Ningbo, Zhang, Zhenyu, Yang, Qiong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.11.2018; Nature Publishing Group
• Subjects: 639/301/119/996; 639/766/119/996; Barium; Barium zirconates; Characterization and Evaluation of Materials; Chemical composition; Chemistry and Materials Science; Computational Intelligence; Ferroelectric materials; Ferroelectricity; Lead free; Materials Science; Mathematical and Computational Engineering; Mathematical and Computational Physics; Mathematical Modeling and Industrial Mathematics; Organic chemistry; Orthorhombic phase; Phase boundaries; Phase transitions; Piezoelectricity; Solid solutions; Theoretical
• ISSN: 2057-3960; 2057-3960
• DOI: 10.1038/s41524-018-0126-3

Barium zirconate titanate [Ba(Zr x Ti 1− x )O 3 ] 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(Zr x Ti 1− x )O 3 because there is no thermodynamic potential. In this paper, a thermodynamic potential for Ba(Zr x Ti 1− x )O 3 (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(Zr x Ti 1− x )O 3 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(Zr x Ti 1− x )O 3 solid solutions. Simulation: thermodynamic potential for solid solutions 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(Zr x Ti 1- x )O 3 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(Zr x Ti 1− x )O 3 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.