Date: Wednesday, May 23rd
Presenter: Prof. Susan Trolier-McKinstry, Materials Science and Engineering Department and Materials Research Institute, The Pennsylvania State University
Piezoelectric thin films are of increasing interest in low voltage microelectromechanical systems for sensing, actuation, and energy harvesting. They also serve as model systems to study fundamental behavior in piezoelectrics. Next generation technologies such as ultrasound pill cameras, flexible ultrasound arrays, and energy harvesting systems for unattended wireless sensors will all benefit from improvements in the piezoelectric properties of the films. This presentation will describe tailoring the composition, microstructure, orientation of thin films, and substrate choice in order to optimize the response. In some cases, improvements in the figure of merit of up to a factor of 10 has been achieved. To improve our fundamental understanding of the evolution of the properties with thickness and mechanical boundary conditions, band excitation piezoelectric force microscopy was used to interrogate the nonlinearity locally. It was found that PbZr0.52Ti0.48O3 thin films show clusters of larger nonlinear response embedded in a more weakly nonlinear matrix. The scale of the clusters significantly exceeds that of the grain size, suggesting that collective motion of many domain walls contributes to the observed Rayleigh behavior in these films. Finally, approaches to lower processing temperatures will be described through the use of pulsed laser annealing.
Susan Trolier-McKinstry is a professor of ceramic science and engineering and director of the W. M. Keck Smart Materials Integration Laboratory at the Pennsylvania State University. Her main research interests include dielectric and piezoelectric thin films, the development of texture in bulk ceramic piezoelectrics, and spectroscopic ellipsometry. She is a fellow of the American Ceramic Society, an academician of the World Academy of Ceramics, a fellow of IEEE, and a member of the Materials Research Society. She is particularly proud that 18 people that she has advised/co-advised have gone on to take faculty positions around the world