2026-06-27T23:00:10Zhttps://docta.ucm.es/rest/oai/request
oai:docta.ucm.es:20.500.14352/340682023-08-26T10:26:56Zcom_20.500.14352_14col_20.500.14352_15
Docta Complutense author Checa, Antonio G. author Mutvei, Harry author Osuna-Mascaró, Antonio J. author Bonarski, Jan T. author Faryna, Marek author Berent, Katarzyna author Pina Martínez, Carlos Manuel author Rousseau, Marthe Rousseau author Macías-Sánchez, Elena 2023-06-19T13:35:03Z 2023-06-19T13:35:03Z 2013 1047-8477 https://hdl.handle.net/20.500.14352/34068 Nacre tablets of mollusks develop two kinds of features when either the calcium carbonate or the organic portions are removed: (1) parallel lineations (vermiculations) formed by elongated carbonate rods, and (2) hourglass patterns, which appear in high relief when etched or in low relief if bleached. In untreated tablets, SEM and AFM data show that vermiculations correspond to aligned and fused aragonite nanogloblules, which are partly surrounded by thin organic pellicles. EBSD mapping of the surfaces of tablets indicates that the vermiculations are invariably parallel to the crystallographic a-axis of aragonite and that the triangles are aligned with the b-axis and correspond to the advance of the {010} faces during the growth of the tablet. According to our interpretation, the vermiculations appear because organic molecules during growth are expelled from the a-axis, where the Ca–CO3 bonds are the shortest. In this way, the subunits forming nacre merge uninterruptedly, forming chains parallel to the a-axis, whereas the organic molecules are expelled to the sides of these chains. Hourglass patterns would be produced by preferential adsorption of organic molecules along the {010}, as compared to the {100} faces. A model is presented for the nanostructure of nacre tablets. SEM and EBSD data also show the existence within the tablets of nanocrystalline units, which are twinned on {110} with the rest of the tablet. Our study shows that the growth dynamics of nacre tablets (and bioaragonite in general) results from the interaction at two different and mutually related levels: tablets and nanogranules. eng Atribución-NoComercial-SinDerivadas 3.0 España Crystallographic control on the substructure of nacre tablets journal article URL https://docta.ucm.es/bitstreams/2cc3fa1c-9048-4a21-8d2b-d62860d4282d/download File MD5 51427ea2a247210a2c4b991560841418 3772637 application/pdf Crystallographic control of nacre, J Struct Biol. Checa et al., 2013-1.pdf