Unveiling the amorphous-to-crystalline transformation mechanisms in calcareous biominerals by Bragg ptychography

This experiment aims at understanding the phase transformation routes involved in the non-classical crystallization of calcareous biominerals leading to the production of large single crystals from amorphous precursors. Two possible mechanisms are proposed, i.e., solid-solid vs dissolution-reprecipitation. We demonstrated with an in vitro model, that a solid-solid transition produces crystalline properties similar to the ones observed in our biogenic model. We now hypothesize that a solid-solid transition is at play in most of calcareous biomineralization. With this proposal, we want to assess the generality of this result, by producing 3D crystalline property maps of a series of biominerals, chosen among different phyla. This proposal exploits the unique features of 3D Bragg ptychography to produce detailed maps of crystalline coherence domains, combined with the drastically improved brilliance of the ESRF-EBS, allowing us to investigate a significant number of large sample volumes.