Achieving High Dielectric Constant Relaxor Ferroelectric Nanocrystals via a Hybridization-Induced Nanodomain Approach

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Nontechnical Abstract:Nanostructured ferroelectric materials show great potential for future micro- and nano-electronic applications, including wearable medical sensors for human monitoring, non-volatile ferroelectric memory, piezoelectric/electrostrictive actuation, second harmonic generation imaging, energy harvesting and storage, electrocaloric cooling, and liquid crystal displays. Unfortunately, as the dimensions of ferroelectric materials decrease to a few tens of nanometers, their high dielectric property eventually disappears as a result of destabilization of the ferroelectric phase. Therefore, it is highly desirable to develop novel, high dielectric constant ferroelectric nanocrystals with stable ferroelectric phase and nanosized domains. The understanding of polymer defect-induced ferroelectric nanodomains within inorganic nanocrystals paves the way to create many other intriguing ferroelectric nanocrystals. Meanwhile, the research project is integrated with nanoscience education through close interactions among graduate students, undergraduate students, high school science teachers, and high school students in a multilevel learning experience inspired by the excitement of discovery at both Georgia Tech and Case Western Reserve University. The goals are to stimulate the interest of high school students in the area of science, technology, engineering, and mathematics (STEM), and better prepare undergraduate students for the STEM-related professions. To enhance the public awareness of nanoscience and nanotechnology, research findings are widely disseminated to multiple constituencies through publications in scientific journals, presentations at national conferences and workshops.Technical Abstract:This proposal aims to understand the effect of organic/inorganic hybridization on the nanoscopic ferroelectric phase and domain structures in polymer-tethered hybrid BaTiO3 nanocrystals, and extend the underlying mechanism to other lead-free relaxor ferroelectric systems to achieve high dielectric constants for various potential electrical applications. First, novel amphiphilic nonlinear block copolymers are rationally designed and synthesized. Subsequently, uniform polymer-tethered hybrid BaTiO3 nanocrystals with precisely tailored dimensions are crafted by employing amphiphilic nonlinear block copolymers as nanoreactors. The nanoscale ferroelectric phase and domain structures in polymer-tethered hybrid BaTiO3 nanocrystals are interrogated using high-resolution transmission electron microscopy, and the mechanism of their relaxor ferroelectric behavior can be unraveled. Finally, the underlying mechanism are extended to create other lead-free relaxor ferroelectric nanocrystals with even higher dielectric constants.