This presentation is an introduction to materials of interest for piezoelectric and ferroelectric applications. The lecture begins with basic definitions of pyroelectricity, piezoelectricity, and ferroelectricity, and the link between these and the symmetry shown by the material is explained. Then, the crystal structures of important piezoelectric systems are introduced, including the wurtzite-structured compounds, the perovskites, the tungsten bronzes, bismuth layer structures, LiNbO3, PVDF, and SbSI. This is followed by an introduction into the domain structures exhibited by ferroelectric materials. Particular emphasis is placed on conditions under which domain walls become mobile, and so contribute to the observed dielectric and piezoelectric properties. This also leads into the distinction between low and high field properties in ferroelectric materials. Finally, key materials are contrasted for a number of different applications, including medical ultrasound transducers, high power transducers, and actuators.
Susan Trolier-McKinstry is a professor of ceramic science and engineering, director of the W. M. Keck Smart Materials Integration Laboratory, and co-director of the cleanroom 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 an active participant in the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society, and has worked in ferroelectrics for 30 years.