1. Innovative Relaxor-Based PiezoCrystals: Phase Diagrams, Crystal Growth, Domain Structures and Electric Properties. 2. Piezo- and Ferroelectric Materials Based on Morphotropic Phase Boundary Synthesis, Characterization and Structure - Property Relations

摘要

This final technical report is on the research work carried out in the area of design, synthesis and characterization of novel piezo- and ferroelectric materials, especially in the form of single crystals, with a view to developing new materials resources for the next generation of electromechanical transducers in a wide range of Navy and civilian applications. Our contributions have covered the following main areas: (a) Thermodynamic analysis and establishment of relevant phase diagrams, which provide information on the solubility and saturation rate, crucial for the growth of large and high quality piezocrystals. (b) Growth of piezocrystals by various techniques. and design and synthesis of new material systems which have been proven, to be very interesting as potential high Tc and high performance piezocrystal resources. (c) Investigation of the complex morphotropic phase diagrams, phase symmetry, domain structures and phase transitions of the most important piezocrystal solid solution systems, which helps illustrate the microscopic mechanisms underlying the extraordinary piezo- and ferroelectric properties. (d) Characterization of a broad spectrum of physical properties, in particular the puzzling structure, dynamics and relaxation of polar nanoregions in relaxors, which has led to the discovery of a new phenomenon of double freezing of two overlapping relaxation processes.