Precipitation of carbonates: recent progress in controlled production of complex shapes

The recent progress in carbonate precipitation with complex shapes mainly concerns CaCO3 due to its importance for industry and biomineralization. Two general morphogenesis approaches were pursued: Either, soluble—predominately polymeric—additives were employed in the precipitation process leading to microparticles with complex shape which are partly even hybrids of two different crystal polymorphs, or macroscopic templates were used as confined reaction environments for precipitation. Despite a considerable amount of work and knowledge gain, the investigation of the structure formation processes with impact on understanding of biomineralization principles still remains a challenge. Nevertheless, some remarkable progress is reported in the areas of template and additive controlled CaCO3 crystallization as well as its morphogenesis based on mesoscopic transformation which lead to a deeper understanding of the underlying structuration principles.