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Structure of Biogenic Aragonite (CaCO 3 )

2007; American Chemical Society; Volume: 7; Issue: 9 Linguagem: Inglês

10.1021/cg060842v

1528-7505

Boaz Pokroy, Andrew N. Fitch, E. Zolotoyabko,

Bone Tissue Engineering Materials

By using high-resolution X-ray powder diffraction at a dedicated synchrotron beam line, ID-31, of the European Synchrotron Radiation Facility (ESRF, Grenoble, France), we studied structural and microstructural modifications in biogenic aragonite crystals, obtained from mollusk shells, and subjected to heat treatments at elevated temperatures. All investigated shells revealed anisotropic lattice distortions of the orthorhombic unit cell as compared to geological aragonite. Annealing at temperatures above 150−200 °C led to pronounced lattice relaxation which is accompanied by a substantial reduction of crystallite sizes and related growth of microstrain fluctuations. These findings indicate that biogenic aragonite crystals are strained, apparently, as a result of the amorphous/crystalline phase transformation, which proceeds within the supporting network of oriented biomacromolecules at early stages of biomineralization.