Xiaoli Tan, Iowa State University, DMR 0346819

1. CAREER: The Evolution of Polar Nanoregions and Its Coupling with Cation-Ordered Domains in Pb(B'B'')O3 Relaxor Ferroelectrics <111> <100> <110> Xiaoli Tan, Iowa State University, DMR 0346819 O The most significant research finding in the past year is that we observed the electric field-induced crystal structure change (phase transformation) in pure Pb(Mg1/3Nb2/3)O3 single crystals. Pb(Mg1/3Nb2/3)O3 is one of the most important compounds used in transducers, actuators, and electrical capacitors. It has a cubic crystal structure as shown in the right. When electric fields were applied along the three crystallographic directions shown in the structure, distinct responses have been observed. The responses are summarized in the E-T phase diagram. In the U-shaped region of the phase diagram, the crystal changes its structure from a cubic to a rhombohedral one under electric fields along all three directions. However, for the <110> direction, there is a further phase transformation to an orthorhombic structure under higher electric fields. Such an electric field-induced phase transformation has not been report previously in pure Pb(Mg1/3Nb2/3)O3 single crystals and is expected to have significant impact on developing new materials with large piezoelectric strains for transducer applications. The research findings have been published in Physical Review B, 75, 104106-1-12 (2007). Mg/Nb Pb

2. CAREER: The Evolution of Polar Nanoregions and Its Coupling with Cation-Ordered Domains in Pb(B'B'')O3 Relaxor Ferroelectrics Xiaoli Tan , Iowa State University, DMR 0346819 The primary educational activity for this CAREER grant is to recruit undergraduate students, with emphasis on underrepresented groups, to the PI’s research lab. In the Summer of 2007 (May through July 2007), one female undergraduate intern from the Lake Forest College, Illinois (Roshnika Fernando) was supported from this project, working on the processing and characterization of a special type of (multiferroic) ceramics. She was selected and recommended by the Program for Women in Science and Engineering (PWSE) at the Iowa State University based on mutual research interest match. Roshnika Fernando was a second-year undergraduate majored in Physics. During the PWSE summer internship, she has been exposed to fundamentals of materials science and trained with basic experimental skills of ceramic processing, electrical properties measurement, and scanning electron microscopy operation. At the end of her internship, she wrote a paper summarizing her research results to the PWSE program and prepared a poster which has been displayed at the graduation event of the 2007 class of PWSE summer interns at the Iowa State University. The poster is shown below.