The Mesoscale Order of Nacreous Pearls
Date
2021-09-02
Authors
Gim, Jiseok
Koch, Alden
Otter, Laura M.
Savitzky, Benjamin H.
Erland, Sveinung
Estroff, Lara A.
Jacob, Dorrit
Hovden, Robert
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National Academy of Sciences (USA)
Abstract
A pearl's distinguished beauty and toughness are attributable to the periodic stacking of aragonite tablets known as nacre. Nacre has naturally occurring mesoscale periodicity that remarkably arises in the absence of discrete translational symmetry. Gleaning the inspiring biomineral design of a pearl requires quantifying its structural coherence and understanding the stochastic processes that influence formation. By characterizing the entire structure of pearls (∼3 mm) in a cross-section at high resolution, we show that nacre has medium-range mesoscale periodicity. Self-correcting growth mechanisms actively remedy disorder and topological defects of the tablets and act as a countervailing process to long- range disorder. Nacre has a correlation length of roughly 16 tab- lets (∼5.5 mm) despite persistent fluctuations and topological defects. For longer distances (>25 tablets, ∼8.5 mm), the frequency spectrum of nacre tablets follows f21:5 behavior, suggesting that growth is coupled to external stochastic processes—a universality found across disparate natural phenomena, which now includes pearls.
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Keywords
nacre, pearls, TEM, SEM, mesoscale
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PNAS - Proceedings of the National Academy of Sciences of the United States of America
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Journal article
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Open Access
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Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY)
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