Direct experimental measurement of water interaction energetics in amorphous carbonates MCO3 (M = Ca, Mn, and Mg) and implications for carbonate crystal growth

A. V. Radha, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Interaction of carbonate surfaces with water plays a crucial role in carbonate nucleation and crystal growth. This study provides experimental evidence for the existence of two different types of water having distinct energetics in amorphous carbonates, MCO3 (M = Ca, Mn, and Mg). The adsorption enthalpy curves obtained using a combination of gas sorption and microcalorimetry show two different energetic regions, which correspond to weakly bound restrictedly mobile and strongly bound rigid H2O components. For weakly bound water, adsorption enthalpies of amorphous calcium carbonate (ACC) (-55.3 ± 0.9 kJ/mol), amorphous manganese carbonate (AMnC) (-54.1 ± 0.8 kJ/mol), and amorphous magnesium carbonate (AMgC) (-56.1 ± 0.4 kJ/mol) fall in the same range, suggesting their interaction modes may be similar in all amorphous phases. Water adsorption enthalpies of crystalline nanocalcite (-96.3 ± 1 kJ/mol) and nano-MnCO3 (-65.3 ± 3 kJ/mol) measured in previous studies are more exothermic than values for ACC (-62.1 ± 0.7 kJ/mol) and AMnC (-54.1 ± 0.8 kJ/mol) and could provide a driving force for crystallization of ACC and AMnC in the presence of water. The differences in water adsorption behavior between amorphous and naocrystalline material have significant implications for crystal growth, biomineralization, and carbonate geochemistry.

Original languageEnglish (US)
Pages (from-to)70-78
Number of pages9
JournalCrystal Growth and Design
Volume15
Issue number1
DOIs
StatePublished - Jan 7 2015
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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