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.  This paper will describe tailoring the composition, microstructure, and orientation of thin films in order to optimize the response.  It will be shown that increases in the grain size of lead-based perovskite films from 75 – 300 nm results in 40 and 20% increases in the permittivity and piezoelectric coefficients, respectively.  This is accompanied by an increase in the nonlinearity in the response.  Band excitation scanning probe microscopy was used to interrogate the nonlinearity locally.  It was found that chemical solution-derived PbZr_0.52Ti_0.48O₃ 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 large scale collective domain wall dynamics underpins the observed Rayleigh behavior in these films.  Finally, approaches to increase the figure of merit for piezoelectric energy harvesting applications will be discussed.

 

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 obtained B.S., M.S., and Ph.D. degrees in Ceramic Science at Penn State, and on graduation, joined the faculty there.  She has held visiting appointments at the Hitachi Central Research Laboratory, the Army Research Laboratory, and the Ecole Polytechnique Federale de Lausanne.  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 past-president of both Keramos and the Ceramics Education Council, and is co-chair of the committee revising the IEEE Standard on Ferroelectricity. She has served as vice-president for ferroelectrics of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society (UFFC), and was an elected member of that group’s administrative committee.  She is currently junior past President of the IEEE UFFC. She is the recipient of the Fulrath and Robert Coble Awards of the American Ceramic Society, a National Security Science and Engineering Fellowship, the Wilson Awards for Outstanding Teaching and Excellence in Research from Penn State’s College of Earth and Mineral Sciences, the Materials Research Laboratory Outstanding Faculty Award, and a National Science Foundation Career grant.  She is particularly proud that 17 people that she has advised/co-advised have gone on to take faculty positions around the world.