[SY-F3] Biomineralization in molluscan shells: From ideal to hierarchical grain growth
Invited
The microstructure of grain networks as they can be found in many polycrystalline materials like metals, alloys, and bionic composite structures have an immense impact on their physical properties. Any change in the structure in terms of the size and shape of the grains leads to a change in the properties. Hence, understanding structural changes is of enormous importance for materials development, processing, and application.
In the present work, we investigate the evolution of the prismatic ultrastructures in molluscan shells in form of a comparative study bringing together large numerical and experimental data sets of molluscan shells from different families. To that aim, a framework has been developed for a quantitative study of the process of shell morphogenesis. The method is based on Monte Carlo Potts model simulations of grain boundary motion that, classically, were developed to study coarsening of polycrystalline metals. By employing this approach, we fully reconstruct the growth process of the different molluscan shells: While the prismatic ultrastructure of Atrina vexillum is an archetype of ideal grain growth fulfilling the classical growth theories, shells like Atrina rigida and Pinna nobilis show retarded growth comparable with triple junction controlled grain growth in nanocrystalline metals, and, finally, the mollusc Pinctada nigra is characterized by a two-level hierarchical prismatic microstructure, which can be represented in the Potts model by introducing sub-grain boundaries.
The proposed framework is a fundamental approach to study the structural regulation during biomineralization.
In the present work, we investigate the evolution of the prismatic ultrastructures in molluscan shells in form of a comparative study bringing together large numerical and experimental data sets of molluscan shells from different families. To that aim, a framework has been developed for a quantitative study of the process of shell morphogenesis. The method is based on Monte Carlo Potts model simulations of grain boundary motion that, classically, were developed to study coarsening of polycrystalline metals. By employing this approach, we fully reconstruct the growth process of the different molluscan shells: While the prismatic ultrastructure of Atrina vexillum is an archetype of ideal grain growth fulfilling the classical growth theories, shells like Atrina rigida and Pinna nobilis show retarded growth comparable with triple junction controlled grain growth in nanocrystalline metals, and, finally, the mollusc Pinctada nigra is characterized by a two-level hierarchical prismatic microstructure, which can be represented in the Potts model by introducing sub-grain boundaries.
The proposed framework is a fundamental approach to study the structural regulation during biomineralization.