The differnces between bond lengths in biogenic and geologocal calcite.

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Crystal Growth and Design

DOI:https://doi.org/10.1021/cg901195t· OSTI ID:1028603

Zlotoyabko, E; Caspi, E N; Fieramosca, J S; Von Dreele, R B; Marin, F; Mor, G; Politi, Y; Addadi, L; Weiner, S ^[1]

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1. X-Ray Science Division

We used high-resolution neutron powder diffraction to accurately measure the atomic positions and bond lengths in biogenic and geological calcite. A special procedure for data analysis was developed in order to take into account the considerable amounts of magnesium present in all the investigated samples. As a result, in biogenic calcite we found some atomic bonds to have significantly different lengths as compared to those in geological calcite, after the contribution of magnesium is accounted for. The maximum effect (elongation up to 0.7%) was found for the C-O bonds. We also analyzed changes in frequencies and spectral widths of normal vibrations of carbonate groups in biogenic calcite (as compared to geological calcite) measured by Raman and Fourier transform IR techniques. Surprisingly, the frequency shifts after subtracting the magnesium contribution are close to zero. At the same time, substantial spectral broadening (up to 1.2%) in biogenic calcite as compared to geological samples was detected. Possible explanations for the experimental findings are discussed.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1028603
• Report Number(s): ANL/XSD/JA-65103
• Journal Information: Crystal Growth and Design, Journal Name: Crystal Growth and Design Journal Issue: 3 Vol. 10; ISSN 1528-7483
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
BOND LENGTHS
CALCITE
CARBONATES
COMPARATIVE EVALUATIONS
DATA ANALYSIS
ELONGATION
FREQUENCY ANALYSIS
LINE BROADENING
LINE WIDTHS
MAGNESIUM
NEUTRON DIFFRACTION
POWDERS