Growth and structure in abalone shell

Lin, Albert; Meyers, Marc A.

doi:10.1016/j.msea.2004.06.072

Cited by 242 publications

(204 citation statements)

References 35 publications

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“…In the example case of abalone, growth is mediated by an organic interlayer comprised of chitin, an organic silk and acidic proteins in such a manner that successive layers of calcium carbonate (aragonite) tablets are deposited (Fig. 10a) [95,[97][98][99][100]. Naturally, the growth of aragonite crystals is highly anisotropic, with the C direction in the orthorhombic cell (normal to the largest surface) having a much greater velocity than either of the orthogonal A or B directions.…”

Section: Mollusk Shellsmentioning

confidence: 99%

Structure and mechanical properties of selected protective systems in marine organisms

Naleway

Taylor

Porter

et al. 2016

Materials Science and Engineering: C

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Section: Mollusk Shellsmentioning

confidence: 99%

Structure and mechanical properties of selected protective systems in marine organisms

Naleway

Taylor

Porter

et al. 2016

Materials Science and Engineering: C

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“…56 Nacre is composed of $95 wt.% aragonite platelets (or tiles) embedded in an organic matrix of chitin. 94 Commonly described as a ''brick-and-mortar'' structure, the aragonite platelets are ''bricks'' that are self-assembled and ''glued'' together by the chitin biopolymer matrix. 95 By freeze casting thin alumina platelets, Hunger et al 96 showed that shear flow induced by ice growth aligns platelets with their long dimension parallel to the freezing direction.…”

Section: Biomimicry Mimicking Bone and Nacrementioning

confidence: 99%

Biomimetic Materials by Freeze Casting

Porter

McKittrick

Meyers

2013

JOM

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Natural materials, such as bone and abalone nacre, exhibit exceptional mechanical properties, a product of their intricate microstructural organization. Freeze casting is a relatively simple, inexpensive, and adaptable materials processing method to form porous ceramic scaffolds with controllable microstructural features. After infiltration of a second polymeric phase, hybrid ceramic-polymer composites can be fabricated that closely resemble the architecture and mechanical performance of natural bone and nacre. Inspired by the narwhal tusk, magnetic fields applied during freeze casting can be used to further control architectural alignment, resulting in freeze-cast materials with enhanced mechanical properties.

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“…In biogenic and synthetic aragonite, indeed we see that it enables the crystals to grow along their caxes, which are the fast growing axes (10× faster than along the a-axes, whereas along the b-axes aragonite only grows 1.6× faster than along the a-axes). 9,80 Moreover, the slight misorientation between neighboring crystals driven by spherulitic growth allows them to fill space efficiently. Other growth geometries, such as a radial cluster of needles with fixed needle width, grow crystals fast along the c-axes but do not fill space.…”

mentioning

confidence: 99%

“…9 Furthermore, subdivision into nanoscale components, as observed in Figure 8, is known to increase materials strength and fracture toughness. 86,87 CONCLUSIONS With quantitative orientation analyses, and comparing abiotically synthesized aragonite spherulites and biogenic aragonite in S. pistillata coral skeletons, we confirm that coral grows spherulitically.…”

mentioning

confidence: 99%

Spherulitic Growth of Coral Skeletons and Synthetic Aragonite: Nature’s Three-Dimensional Printing

Sun¹,

Marcus

Frazier³

et al. 2017

ACS Nano

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Coral skeletons were long assumed to have a spherulitic structure, that is, a radial distribution of acicular aragonite (CaCO 3 ) crystals with their c-axes radiating from series of points, termed centers of calcification (CoCs). This assumption was based on morphology alone, not on crystallography. Here we measure the orientation of crystals and nanocrystals and confirm that corals grow their skeletons in bundles of aragonite crystals, with their caxes and long axes oriented radially and at an angle from the CoCs, thus precisely as expected for feather-like or "plumose" spherulites. Furthermore, we find that in both synthetic and coral aragonite spherulites at the nanoscale adjacent crystals have similar but not identical orientations, thus demonstrating by direct observation that even at nanoscale the mechanism of spherulite formation is non-crystallographic branching (NCB), as predicted by theory. Finally, synthetic aragonite spherulites and coral skeletons have similar angle spreads, and angular distances of adjacent crystals, further confirming that coral skeletons are spherulites. This is important because aragonite grows anisotropically, 10 times faster along the c-axis than along the a-axis direction, and spherulites fill space with crystals growing almost exclusively along the c-axis, thus they can fill space faster than any other aragonite growth geometry, and create isotropic materials from anisotropic crystals. Greater space filling rate and isotropic mechanical behavior are key to the skeleton's supporting function and therefore to its evolutionary success. In this sense, spherulitic growth is Nature's 3D printing. KEYWORDS: Ion attachment, crystallization by particle attachment, CPA, biomineralization, PEEM, PIC-mapping, mesocrystal S pherulites are polycrystalline structures in which acicular crystals radiate from a common center and grow approximately synchronously so the final shape of a spherulite resembles a sphere. 1−7 Figure 1 shows two types of spherulites: "spherical spherulite", in which the crystal fibers start from a point, or "plumose spherulite", in which crystal fibers radiate at an angle from the line. 7 Spherulites start forming as an aggregate of parallel acicular crystals termed "fibers", then form a "sheaf of wheat" structure, and with the growth of more fibers eventually become complete spheres. 8 In an ideal spherulite, fibers radiate from the center and contain all possible orientations within the sphere. Since the fast-growing axis in aragonite (CaCO 3 ) is the c-axis, 9 in spherulites each fiber elongation direction coincides with the crystalline c-axis. 10,11 In real spherulites, biogenic 12 and synthetic, 7 the crystal orientations are not perfectly radial nor continuously varying with angle, they deviate slightly from radial and exhibit small but abrupt changes in orientation, termed "branching". In Figure 1 branching angles are smaller than 30°in direction and in crystal lattice orientation. This is distinct from crystallographic branching, which occurs in sno...

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Growth and structure in abalone shell

Cited by 242 publications

References 35 publications

Structure and mechanical properties of selected protective systems in marine organisms

Structure and mechanical properties of selected protective systems in marine organisms

Biomimetic Materials by Freeze Casting

Spherulitic Growth of Coral Skeletons and Synthetic Aragonite: Nature’s Three-Dimensional Printing

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