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Probing Local Origins of Nonlinearity in Ferroelectric Films Susan E. Trolier-McKinstry , Pennsylvania State Univ University Park, DMR 1005771.
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Probing Local Origins of Nonlinearity in Ferroelectric FilmsSusan E. Trolier-McKinstry, Pennsylvania State Univ University Park, DMR 1005771 Outcome: The length scale at which ferroelectric domain walls are influenced by a single grain boundary was determined for the first time to be 600 - 800 nm. Impact: Ferroelectric material are important in a host of applications, including medical ultrasound transducers. The sensitivity of the ferroelectric depend on the mobility of domain walls. We are now unpicking the factors that control that mobility. Explanation: Piezoresponse force microscopy was used to map the nonlinear piezoelectric response in epitaxial PbZr0.45Ti0.55O3 thin films grown on bicrystal substrates. It was found in samples of several different thicknesses that there is a region of material which averages 600 – 800 nm in width around the grain boundary where the domain walls respond more weakly to an applied electric field. This is correlated with a change in domain structure at a similar length scale. The bicrystal boundary reduces the coupling of high response regions from one side to the other. Nonlinear response map Dark lines: Domain walls in PZT film Bicrystal boundary
Pondering the Nanometer Scale with 8th GradersSusan E. Trolier-McKinstry, Pennsylvania State Univ University Park, DMR 1005771 Graduate students Dan Marincel and Jon Bock along with Prof. Susan Trolier-McKinstry built models of graphite, graphene, and single walled carbon nanotubes with three classrooms of 8th grade students at Park Forest Middle School. Each student built their own models, so they could understand the way in which atoms connect. We related the lesson to the chemistry they were learning and talked about the implications of the structure in terms of properties. Students were particularly engaged by the carbon nanotubes and the implications for very high strength materials. Models built with advanced chemistry students at Park Forest Middle School front to back: graphite, buckeyball, and carbon nanotubes