Materials World Network: Effects of Constraints and Thickness on Perovskite Ferroelectrics Undergoing Tilt Transitions

Susan E. Trolier-McKinstry, Pennsylvania State Univ University Park, DMR 0602770

With the support of NSF funding, researchers at the Pennsylvania State University have learned how to engineer the temperature stability of AgTa0.5Nb0.5O3, a material for microwave resonators, by shifting the critical transition temperature ~ 200°C. In PbZr1-xTixO3 films, it was shown that strain increases the ferroelectric phase transition temperature much more quickly than the tilt transition temperatures. This opens up the possibility of new, lead-free piezoelectric thin films with large response coefficients for miniature sensors, actuators, and energy harvesting systems.Figure Captions: (top) Measured phase transition sequence of epitaxial AgTa0.5Nb0.5O3 films. The M2/M3 transition temperature has been decreased by ~200°C, while the Orthorhombic (O), tetragonal (T) and cubic (C) phases are little changed. (bottom) M3 tilted phaseCredit: S.E. Trolier-McKinstry Permission to NSF granted.

M3 tilted phase

AgTa0.5Nb0.5O3

>150 4th grade students and their teachers at Radio Park Elementary school in Pennsylvania built models of the crystal structures of rocksalt and graphite. The students were taught about atoms, symmetry, bonding and how piezoelectricity works.

Significance of broader impacts: Two graduate students have received international training, in addition to their Penn State research work. Both intend to become faculty members in the future.

Significance to society: New materials for smaller, lighter cell phone components were developed. A route that may enable lead-free CMOS-compatible piezoelectric sensors and actuators was developed

Students learn about Crystals in the Fourth Grade Susan E. Trolier-McKinstry, Pennsylvania State Univ University Park, DMR 0602770