Ms. Lior Weiss - M.Sc. Candidate
11/10/2026
David Wang Auditorium, 3rd Floor, Dalia Maydan Bldg.
13:30
Amorphous calcium carbonate (ACC) is a metastable, hydrated precursor phase from which crystalline calcium carbonate polymorphs form. Its disordered structure is exploited by organisms to guide mineral growth in ways difficult to reach by direct precipitation, and it readily incorporates foreign ions and molecules. Beyond conventional solution-mediated routes, both mechanical stress and thermal processing can alter how ACC transforms into crystalline phases. In this work, we examine how mechanical compression of bulk ACC and thermal treatment of ACC thin films affect phase selection, ion incorporation, and crystallization outcomes.
We first subjected ACC precursors containing inorganic (Mg²⁺) and organic (amino acids) additives to mechanical compression spanning from 74 to 1110 MPa. Magnesium promoted calcite formation with increasing pressure and was incorporated into the lattice in a concentration-dependent manner, while amino acids kinetically stabilized the metastable vaterite across the entire pressure range studied. When magnesium and an amino acid were combined, the outcome fell between their individual effects, suggesting the additives compete for incorporation. These results show that polymorph selection under pressure is governed by an interplay between a mechanical driving force and precursor chemistry.
We also studied the effect of thermal treatment on spray-deposited ACC thin films on soda-lime glass. Rather than forming calcium carbonate crystals, thermal treatment triggered leaching of sodium from the glass onto the surface, which then reacted with chlorine present in the environment or retained in the precursor to form well-ordered sodium chloride crystals, densely distributed, with size and density depending on temperature and magnesium content.
Overall, this work shows that additive chemistry, applied pressure, and substrate interactions can each exert control over crystallization pathways and dopant incorporation from an amorphous precursor.