Nanodomain Structure of Magnesium‐Stabilized Amorphous Calcium Carbonate Prepared in Aqueous Solution
Journal
Journal of the Chinese Chemical Society
ISSN
0009-4536
2192-6549
Date Issued
2026-05-21
Author(s)
Abstract
Magnesium-stabilized amorphous calcium carbonate (Mg-ACC) is a key precursor for biogenic Mg-calcite. Biogenic Mg-calcite is not a single phase but comprises Mg-rich calcitic nanodomains embedded within an Mg-depleted calcitic matrix, a structural heterogeneity that enhances fracture toughness compared with geological calcite. In a recent study of Mg-ACC monoliths prepared in ethanol, Mg-rich amorphous nanodomains (MgR) within an Mg-depleted amorphous matrix (MgD) were identified; however, it remains unclear whether the same structural heterogeneity exists in aqueous systems. Here, advanced solid-state NMR techniques were applied to demonstrate that MgD and MgR nanodomains coexist in Mg-ACC powders prepared in aqueous solution. Notably, MgR and MgD domains are well integrated only when the total Mg content in Mg-ACC is below ~16 mol%. In addition, a hydroxyl structural motif is identified in Mg-ACC, with its abundance increasing at higher Mg content.
Subjects
amorphous calcium carbonate
LLPS
pre-nucleation cluster
S-RESPDOR
solid-state NMR
spin diffusion
Publisher
Wiley
Type
journal article