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Homoepitaxial meso- and microscale crystal co-orientation and organic matrix network structure in Mytilus edulis nacre and calcite

Paper ID Volume ID Publish Year Pages File Format Full-Text
652 53 2013 11 PDF Available
Title
Homoepitaxial meso- and microscale crystal co-orientation and organic matrix network structure in Mytilus edulis nacre and calcite
Abstract

New developments in high-resolution, low accelaration voltage electron backscatter diffraction (EBSD) enable us to resolve and quantify the co-orientation of nanocrystals constituting biological carbonate crystals with a scan step resolution of 125 nm. This allows the investigation of internal structures in carbonate tablets and tower biocrystals in the nacre of mollusc shells, and it provides details on the calcite–aragonite polymorph interface in bivalves. Within the aragonite tablets of Mytilus edulis nacre we find a mesoscale crystallographic mosaic structure with a misorientation distribution of 2° full width at half maximum. Selective etching techniques with critical point drying reveal an organic matrix network inside the nacre tablets. The size scales of the visible aragonite tablet subunits and nanoparticles correspond to those of the open pore system in the organic matrix network. We further observe by EBSD that crystal co-orientation spans over tablet boundaries and forms composite crystal units of up to 20 stacked co-oriented tablets (tower crystals). Statistical evaluation of the misorientation data gives a probability distribution of grain boundary misorientations with two maxima: a dominant peak for very-small-angle grain boundaries and a small maximum near 64°, the latter corresponding to {1 1 0} twinning orientations. However, the related twin boundaries are typically the membrane-lined {0 0 1} flat faces of the tablets and not {1 1 0} twin walls within tablets. We attribute this specific pattern of misorientation distribution to growth by particle accretion and subsequent semicoherent homoepitaxial crystallization. The semicoherent crystallization percolates between the tablets through mineral bridges and across matrix membranes surrounding the tablets. In the “prismatic” calcite layer crystallographic co-orientation of the prisms reaches over more than 50 micrometers.

Keywords
Mesocrystal; Biomineralization; Hybrid nanocomposite; Hierarchical architecture; Abalone
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Homoepitaxial meso- and microscale crystal co-orientation and organic matrix network structure in Mytilus edulis nacre and calcite
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Publisher
Database: Elsevier - ScienceDirect
Journal: Acta Biomaterialia - Volume 9, Issue 12, December 2013, Pages 9492–9502
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us