Stability and Dynamics of Mesoscale Microstructure

9633719 Chen Theoretical studies will be made of the stability and dynamic evolution of mesoscopic microstructures during phase transformations and materials processing. The main objective is to develop a unified model which can efficiently be employed to study not only the multi-domain structures with competing short- and long-range interactions in a single crystal, but also the multi-grain and multi- phase microstructures in ceramic materials of technological interest. A continuum field approach is used and three specific problems will be investigated: domain formation and dynamics in ferroelectric oxides as a result of competing electrostatic energy, elastic energy and domain wall energy; the formation of nanoscale ordered domains in relaxor ferroelectrics; and, the kinetics of microstructural evolution in multi-grain materials driven by the reduction in the total interfacial energy. %%% This grant studies an important fundamental problem in materials research which has critical technological implications. Namely, analytical and numerical methods will be used to study and understand the evolution of microstructure in materials as they go through changes in phase. This is an extremely difficult fundamental problem which directly impacts materials processing. The particular systems to be studied are ceramic materials in which control of the microstructure has direct bearing on material proerties. Of special interest in this research will be ferroelectric materials which have applications as sensors and optical components. ***