ChBE Seminar Series: Defect Engineering in Molecular Crystals
Speaker: Jennifer Swift, Professor of Chemistry, Georgetown University
Title: Defect Engineering in Molecular Crystals
It is well known that lattice defects can affect the physical properties of crystalline materials. Over the past several years, we have been working to understand how doping molecular crystal systems can be used to tailor their physical properties. With uric acid as a model system, this talk will describe how the inclusion of dye molecules (at 0.01-1 wt %) in both the hydrated and anhydrous forms can be used as a means to intentionally create substitutional defects which can be spectroscopically quantified. Large differences were observed in the morphological, thermal and mechanical properties of pure and doped single crystals. In particular, nanoindentation studies showed that the Young’s modulus of dye-doped crystals was up to 50% lower than pure crystals, owing to dopant inclusions acting as new dislocation sources which increase plasticity. However, with progressively higher doping loads, a competing material hardening effect was observed due to the pinning of dislocation movement.
Jennifer Swift earned her B.A. from Bowdoin College (ME) and Ph.D. from Yale University (CT), both in the field of Chemistry. After two years of postdoctoral studies at the University of Minnesota in the Department of Chemical Engineering and Materials Science, she began her independent career in 1999 in the Chemistry Department at Georgetown University. Her work on molecular crystal growth and properties has been funded, primarily, over the years by the NSF, DTRA and the Clare Booth Luce Foundation. Swift will chair the 2020 Gordon Research Conference on Crystal Engineering this summer.