Nanocrystallite model for amorphous calcium carbonate

Peter Rez, S. Sinha, A. Gal

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Amorphous calcium carbonate phases, either synthesized artificially or generated biogenically, can be identified from broadened peaks in X-ray or electron diffraction profiles. It is conceivable that randomly oriented nanocrystals, approximately 1 nm in size, could give rise to coherent diffraction profiles that are characterized as amorphous. The coherent diffraction profiles for 200 keV electrons, as might be used in an electron microscope, and Cu Kα X-rays were calculated for needle-shaped calcite crystals bounded by {1121} facets and rhomb-shaped crystals bounded by {1014} facets. Crystals of about 1.0 nm in size gave a profile that is consistent with the X-ray measurements of amorphous calcium carbonate. The relative intensity of high-angle broadened peaks and changes in the IR spectrum are best explained by disorder in the nanocrystallites. The presence of randomly oriented nanocrystallites also explains the lack of optical birefringence.

Original languageEnglish (US)
Pages (from-to)1651-1657
Number of pages7
JournalJournal of Applied Crystallography
Issue number5
StatePublished - Oct 2014


  • amorphous calcium carbonate
  • nanocrystals

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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