1. MPB Materials World Network: Effects of Constraints and Thickness on Perovskite Ferroelectrics Undergoing Tilt TransitionsCo-PI’s: (Penn State), Stephen Streiffer (Argonne National Lab.)International Collaborator: Prof. Ian M. Reaney (University of Sheffield)Award #: Materials World Network proposal, DMR-0602770 Piezoelectric materials are used in medical imaging and therapeutic ultrasound systems, non-destructive testing, actuators, flow meters, precision positioning devices, a wide variety of sensors (e.g. accelerometers, cardiac health monitors) timing standards, oscillators, and resonators. Many of the key materials for these applications contain lead, and so are of environmental concern. Unfortunately, to date, comparable properties have not been achieved in lead-free systems. Researchers at the Pennsylvania State University have recently predicted and experimentally identified a morphotropic phase boundary (MPB) coupled with a high dielectric permittivity (See Fig.) in the lead-free BiScO3 – BaTiO3 system. These two factors are strongly correlated with high piezoelectric constants. Thus, work is currently underway to develop this system as a base composition for lead-free piezoelectrics.