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AAA5.02 - Structural Analysis of Calcium Carbonate Mesocrystals 
April 23, 2014   11:00am - 11:15am

The term mesocrystal has been used to describe large, 3D particles which diffract as single crystals and yet exhibit internal structures comprising oriented nanoparticles. Evidence for mesocrystal structures is therefore based on structural analysis of crystalline particles by techniques including scanning electron microscopy (SEM), surface area analysis (BET), and transmission electron microscopy (TEM) of thin sections. Here, we use calcium carbonate as a model system to evaluate the effectiveness of these techniques for identifying a nanoparticulate sub-structure. Indeed, although it is now common-place to assign mesocrystal structures based on broadening of XRD peaks and apparent nanoparticulate surface structures, we demonstrate that both of these approaches have to be treated with care. Therefore, high resolution synchrotron XRD analysis demonstrates that line broadening often arises from lattice strain rather than a subunit structure. Finally, electron backscattered X-ray diffraction (EBSD) is used to provide a direct structural comparison of biogenic calcite mesocrystals with their synthetic counterparts.

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Keynote Address
Panel Discussion - Different Approaches to Commercializing Materials Research
Business Challenges to Starting a Materials-Based Company
Fred Kavli Distinguished Lectureship in Nanoscience
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