IMF2017

Our experimental results and analyses on the relationship among the compositions, crystalline structures and properties will be presented for two types of ferroelectric materials: potassium sodium niobate (KNN)-based lead-free ceramics and polyvinylidene fluoride (PVDF)-based polymers, both derived from non-crystalline precursors. The lead-free ceramic films were obtained by chemical solution method and thermal spray method, respectively, with controlled composition and crystallinity, and outstanding piezoelectric performance properties. In the chemical solution method for producing the KNN-based thin films, combinational chemical stabilizing agents were dedicatedly selected and introduced in the precursor solution for effectively suppressing volatile compositional loss; In the thermal spray process for the ceramic thick films, the extremely high melting and cooling rate significantly restricted the volatile loss and decomposition at high temperature. The mechanism of forming the high quality piezoelectric perovskite crystalline phase from the non-crystalline precursors will be analyzed in contrast to that of ceramic synthesis through solid state reaction of the oxide reactants. For the ferroelectric PVDF-based thin films and nanotubes, the crystallization of the polar phase and polarization orientation were controlled by addition of selective hydrated salts and an interesting nano-confinement effect, respectively. Superior piezoelectric performance properties will be highlighted in our nanostructured ferroelectric PVDF-based polymers with highly aligned polarization. The strategy for obtaining the excellent piezoelectric performance properties in the ferroelectric lead-free ceramic and polymer materials from the non-crystalline precursors will be addressed. Finally, examples of piezoelectric devices realized with our obtained high performance ferroelectric materials will be introduced.