Friday, November 19, 2010 3:00 pm – 4:00 pm (1 of 2 speakers)
Room 610, M&M Building
Materials Science and Engineering
Michigan Technological University
Phase field modeling and computer simulation is performed to study the mechanisms ofcrystallographic domain engineering technique for ferroelectrics. It is found that both domainconfigurations and domain sizes in ferroelectric single crystals can be controlled throughsophisticated thermal and electrical conditions imposed on the materials during ferroelectricphase transformations. The simulations reveal that minimal domain sizes and highest domainwall densities are obtained with intermediate magnitude of electric field applied along non-polaraxis of ferroelectric crystals, while lower and higher fields produce coarser domains and lowerdomain wall densities. It is found that temperature also plays an important role in domain sizecontrol. The simulations show that selection of polar domain variants by external electric fieldduring nucleation stage of ferroelectric phase transition significantly affects subsequent domaingrowth and evolution kinetics and controls the formation and sizes of twin-related lamellardomains. It is also found that the long-range electrostatic and elastostatic interactions generateinsurmountable energy barrier to isolated ferroelectric nucleation, and independent nucleation offerroelectric phase in the context of classical nucleation theory is impossible. In order tocircumvent such an energy barrier, ferroelectric nucleation exhibits strong spatial correlation andself-organization behaviors, and ferroelectric phase transformation proceeds via spatial andtemporal evolution of self-accommodating domains that provide a low-energy kinetic pathwaythroughout the entire phase transformation process.