Griesshaber, Erika; Ubhi, Harvinder Singh; Schmahl, Wolfgang W.
Nanometer scale microstructure and microtexture of biological materials revealed by high spatial resolution (15 to 5 kV) EBSD.
In: Tewari, A.; Suwas, S.; Srivastava, D.; Samajdar, I.; Haldar, A. (eds.) :
TEXTURES OF MATERIALS, PTS 1 AND 2. Vol. 702. pp. 924-927
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High resolution EBSD analysis was carried out under specificexperimental conditions (15 to 5 kV) on the skeleton of the moderncarbonate brachiopod Gryphus vitreus and resolved nano- to microscalepreferred crystallographic orientation patterns undetcted so far. Asbiologic superstructures are formed by controlled nanoparticle assemblyit is essential to resolve their internal structure and texture with thehighest possible spatial resolution. Low kV EBSD (15 kV and at 5 kV)provides the required resolution. We observe in the investigatedcarbonate skeletons a strongly interlocking microstructure ofconcave/convex grains. The interface topology of the interdigitatingstructure reaches below the micrometer scale. Individual grains reachsizes up to 20 mu m (or even more) in one dimension. They show a mosaicspread of several degrees such that they must be addressed asmesocrystals. Even though the shell consists of three differentmicrostructures with completely different crystal morphologies and grainboundary topologies the crystallographic texture of the three layers issimilar. This indicates that distinct control mechanisms prevail whenthe shell is formed.