Figure 2: Structure of the pre-nacre nanocrystals showing a typical diameter of 50–80 nm. | Nature Communications

Figure 2: Structure of the pre-nacre nanocrystals showing a typical diameter of 50–80 nm.

From: Nanoscale assembly processes revealed in the nacroprismatic transition zone of Pinna nobilis mollusc shells

Figure 2

(a) Planar view of the packing in pre-nacre aggregation region. (b,c) Pair of annular dark-field (HAADF) and bright-field (BF) STEM images taken in the same region. The BF image of nanocrystals clearly reveals polycrystallinity among the particles and within each particle; twin boundaries running end to end are highlighted with arrows. (d) SAED shows that the nanocrystallites are consistent with the aragonite CaCO3 polymorph—the same polymorph of mature nacre. (e) Plot of radially integrated SAED intensity with known aragonite peaks marked along the x axis; background of plot e is a polar transformation of d over 0–5 radians. Scale bars, (a) 200 nm; (b,c) 50 nm.

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