Design, synthesis, and characterization of high-temperature and high-performance piezo-/ferroelectric perovskite materials

Perovskite materials, which constitute one of the most important categories of functional materials due to their superior piezo-/ferroelectric properties, have attracted enormous research interest in materials science and engineering. Rising demands for advanced electromechanical transducers in a wide range of applications have set the challenge for perovskite materials to not only exhibit good piezo-/ferroelectric performance but also to be able to function over wider temperature and electric field ranges. The currently commercial piezo-/ferroelectric perovskite materials suffer from serious issues like a low Curie temperature TC, an even lower phase transition temperature TMPB, and a low coercive field, which makes them unsuitable for high-temperature and/or high-power electromechanical transduction applications. This thesis work focuses on developing high-temperature and high-performance piezo-/ferroelectric perovskite materials, and establishing the structure-property relationships in the available perovskite material systems. Under this objective, a few promising material systems, including the new bismuth-based complex perovskite solid solution (1-x)PbTiO3-xBi(Zn2/3Ta1/3)O3 (BZTa-PT) in the form of ceramics and single crystals, the pseudo-binary (1-x)(0.35BiScO3-0.65PbTiO3)-xPbZrO3 (BS-PT-xPZ) ceramics, and the single crystals of 0.33Pb(Yb1/2Nb1/2)O3-0.23PbZrO3-0.44PbTiO3 (0.33PYN-0.23PZ0.44PT) and 0.25BiScO3-0.17PbZrO3-0.58PbTiO3 (0.25BS-0.17PZ-0.58PT) ternary systems, have been developed in this work. These material systems show high Curie temperatures, enhanced coercive fields, and competitive piezoelectric performance. They constitute new families of piezo-/ferroelectric materials for high-temperature and high-power electromechanical applications. Furthermore, the structure-property correlations in bismuth-based perovskite solid solutions, such as the structural origin for non-monotonic TC trend, the tetragonality relationship with TC and piezo-/ferroelectric performance, the crystal chemistry correlations between piezo-/ferroelectricity and morphotropic phase boundary (MPB), are established, which provide a more insightful understanding of the structure-property correlations in these material systems and a comprehensive guidance for the design and development of novel high-performance piezo-/ferroelectric materials in the future.