Formation and ageing of L‐glutamic acid spherulites

Beck, Ralf; Malthe‐Sørenssen, D.; Andreassen, Jens‐Petter

doi:10.1002/crat.201000125

Cited by 7 publications

(12 citation statements)

References 16 publications

(19 reference statements)

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“…Spherulitic growth is observed most frequently in crystals formed ion-byion from solution 43 , in sulphates 49,50 and oxalates 51 , or via phasetransformation, for instance in the case of glass to crystalline phase, e.g. in small organic molecules 52,53 , or crystallization of polymers from the melt, e.g. in plastics 54 or metals 54,55 .…”

Section: Discussionmentioning

confidence: 99%

Narrowly Distributed Crystal Orientation in Biomineral Vaterite

et al. 2015

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Biominerals formed by animals provide skeletal support, and many other functions. They were previously shown to grow by aggregation of amorphous nanoparticles, but never to grow ion-by-ion from solution, which is a common growth mechanism for abiotic crystals. We analyze vaterite (CaCO3) multi-crystalline spicules from the solitary tunicate Herdmania momus, with Polarization-dependent Imaging Contrast (PIC)-mapping, scanning and aberration-corrected transmission electron microscopies. The first fully-quantitative PIC-mapping data, presented here, measured 0°-30° angle spreads between immediately adjacent crystals. Such narrowly distributed crystal orientations demonstrate that crystallinity does not propagate from one crystal to another (0° angle spreads), nor that new crystals with random orientation (90°) nucleate. There are no organic layers at the interface between crystals, hence a new, unknown growth mechanism must be invoked, with crystal nucleation constrained within 30°. Two observations are consistent with crystal growth from solution: vaterite microcrystals express crystal faces, and are smooth at the nanoscale after cryo-fracture. The observation of 30° angle spreads, lack of interfacial organic layers, and smooth fracture figures broadens the range of known biomineralization mechanisms and may inspire novel synthetic crystal growth strategies. Spherulitic growth from solution is one possible mechanism consistent with all these observations.

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Section: Discussionmentioning

confidence: 99%

Narrowly Distributed Crystal Orientation in Biomineral Vaterite

et al. 2015

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“…17 Rodrigues-Navarro also showed this effect. 18 Thus, both aragonite growth by CPA and by ion attachment are faster along the c-axis.Spherulites are found in a wide variety of materials systems, including geologic minerals, 19,20 metal alloys, 21 nonmetallic elements, 5,22 salts, 23,24 organic molecules, 13,25 proteins, 26 and a vast number of synthetic 2,3,27,28 and natural 4 polymers.Many biominerals have also been described as spherulitic based on their morphologies, including coral skeletons, 10,11,29,30 avian eggshells, 31−33 fish otoliths, 12,34,35 crustacean statoliths, 36 sponges, 37 and kidney stones. 38,39 The only evidence of spherulites in biominerals obtained from crystal orientation analysis, however, is in bioinduced, kidney stones, which are calcium oxalate monohydrate pathological biominerals.…”

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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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“…5). The observation of the flakes is reminiscent of the behaviour of L-glutamic acid crystals [10] after 3 h of crystallization and could indicate a modification of crystal-solution interaction during the crystallization process. The cake resistance of 1,8·10 11 m/kg is higher than for experiments in which the stirring speed was kept constant at 500 rpm (6,1·10 10 m/kg) which can also be accounted for by the lower measured mean chord length of 12.4 µm as compared to 16.1 µm (unweighted).…”

Section: Resultsmentioning

confidence: 90%

“…Louhi-Kultanen et al [15], for example studied the ageing of crystalline potassium sulphate and found that 60 min ageing time decreased the cake resistances whereas cake porosities varied only slightly between fresh and aged precipitates. As a further example, Beck et al [10] have shown that the average specific cake resistance of L-glutamic decreases when kept in a stirred aqueous solution for 22 h. Like for the aromatic amine, differences in the XRD spectra of crystals from different time intervals have been shown to be marginal, if they exist at all.…”

Section: Resultsmentioning

confidence: 95%

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Ageing of spherulites of an industrial relevant aromatic amine derivative

Beck¹,

Heskestad

Malthe‐Sørenssen

et al. 2010

Cryst. Res. Technol.

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Polycrystalline spherulites of an aromatic amine derivative have been precipitated in a batch process by pHshift with hydrochloric acid from stirred aqueous solutions. The time dependent behaviour of the spherulites has been studied during crystallization in the temperature range from 5 °C to 60 °C. Cake resistance values have been obtained from batch filtration tests performed at 2 bar pressure difference at different stages of the crystallization process. The FBRM mean chord length of the crystals decreases with time as a result of crystal ageing into plate-like crystals. The rate of the ageing process increases with temperature. XRD-studies show no significant differences in the crystal structure during the ageing process, and the mechanism of the transformation was not established. The filterability of aromatic amine crystals deteriorates as the crystallization progresses. The decrease in the filterability is attributed to the appearance of small plate-like crystals and a change in the interaction between the crystal surface and the solution, during the ageing of the particles.

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Formation and ageing of L‐glutamic acid spherulites

Cited by 7 publications

References 16 publications

Narrowly Distributed Crystal Orientation in Biomineral Vaterite

Narrowly Distributed Crystal Orientation in Biomineral Vaterite

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

Ageing of spherulites of an industrial relevant aromatic amine derivative

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