Unveiling different phase transformation mechanisms in Calcite crystallization by Bragg ptychography

This experiment aims at characterizing and understanding the phase transformations involved in the non-classical crystallization of calcite films with organic mediation. Theory proposes two possible mechanisms to describe the amorphous-to-crystal transformation, i. e., solid-solid vs dissolution-reprecipitation. We developed an in vitro model, allowing us to choose either of the two by tuning temperature and humidity during the crystallization. To confirm the existence of these mechanisms and provide a detailed description of the formed crystal, we propose to use 3D Bragg Ptychography. We anticipate obtaining data on a drastically larger sample volume and from several Bragg peaks. This allows to study the local variations in the process of the crystallization and obtaining the full strain tensor in every voxel in order to understand the growth process. This proposal will bring fundamental knowledge on the ubiquitous, but ill-known processes underlying non-classical crystallisation.