Regensburg 2007 – wissenschaftliches Programm

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SYBM: Symposium Bioinspired Materials

SYBM 1: Symposium Bioinspired Materials

SYBM 1.2: Hauptvortrag

Donnerstag, 29. März 2007, 10:00–10:30, H1

On the structure of biogenic CaCO₃ — •B. Pokroy — Department of Materials Engineering, Technion Israel Institute of Technology, Technion City, Haifa 32000 (Israel)

Organisms produce a large number of minerals in the course of biomineralization. These biogenic minerals have been extensively studied because of their fascinating mechanical, optical and magnetic characteristics and their capability to effectively control the polymorph selection and crystal morphology. Calcium carbonate, CaCO₃, is by far the most abundant biogenic mineral and it exists in different structural forms (listed in the order of descending thermodynamic stability at normal conditions): calcite, aragonite, vaterite and amorphous calcium carbonate.

By performing accurate structural measurements by high-resolution x-ray powder diffraction on a synchrotron beam line the unit cell parameters of biogenic CaCO₃ crystals were found to be slightly distorted as compared to that of their geological counterparts. Moreover, neutron diffraction revealed that the atomic bonds of these biogenic crystals are also distorted.

I will show that these structural distinctions are caused by intra-crystalline organic molecules.

Theses results imply that organisms can control biogenic crystals on the nm scale.