CAREER: The Evolution of Polar Nanoregions and Its Coupling with Cation-Ordered Domains in Pb(B'B'')O3 Relaxor Ferroelectrics

Iowa State University, Ames IA

Investigators

Abstract

This CAREER project addresses the interactions between the polar nanoregions and the cation ordering domains and the effects of the chemical domains on the dynamic transition of the polar domains in relaxor ferroelectrics of complex perovskite Pb(B'B")O3. These two types domains are both on the nanometer scale and their interplay is the physical origin for the observed superior properties. Application of an electric field leads to a transformation of the polar regions into ferroelectric macrodomains, corresponding to a first order phase transition. However, our current understanding of the coupling between these two nanoscale features is very limited and the evolution of the polar nanodomains in the presence of external fields has never been explored. A unique in situ transmission electron microscopy (TEM) approach will be taken in this study in order to deliver electric voltage to TEM specimens at controlled low temperatures. This experiment seeks to visualize, in real time, the evolution of fundamental nanoscale features in relaxor ceramics. The results derived from this project are significant because they are expected to (i) identify the coupling between chemical order and electric dipole order, (ii) establish the mechanism of the field-induced phase transition, and (iii) refine existing kinetics models for better understanding of relaxor behavior. The research findings will be treated within the broader context of nanomaterials science and utilized for nanoscience education. Integrated educational activities will be pursued to promote nanoscience education by exposing a large number of students at various levels to this new knowledge. The science and application of nanomaterials will be introduced into the K-12 curriculum through a series of summer workshops for Iowa high school science teachers and Web-based lesson plans for 5th-8th graders created by high school interns. As an underrepresented group, women will be involved through the Iowa State University's Program for Women in Science and Engineering (PWSE) and the Internet Explorers program of the College of Engineering.