On the structure of amorphous calcium carbonate – a detailed study by solid-state NMR spectroscopy

In: Inorganic Chemistry, Jg. 47 (2008) ; Nr. 17, S. 7874-7879
ISSN: 1520-510X
Zeitschriftenaufsatz / Fach: Chemie
The calcium carbonate phases calcite, aragonite, vaterite, monohydrocalcite (calcium carbonate monohydrate), and ikaite (calcium carbonate hexahydrate) were studied by solid-state NMR spectroscopy (1H and 13C). Further model compounds were sodium hydrogencarbonate, potassium hydrogencarbonate, and calcium hydroxide. With the help of these data, the structure of synthetically prepared additive-free amorphous calcium carbonate (ACC) was analyzed. ACC contains molecular water (as H2O), a small amount of mobile hydroxide, and no hydrogencarbonate. This supports the concept of ACC as a transient precursor in the formation of calcium carbonate biominerals.