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Title: Experimental and computational study of thaumasite structure

The structure of thaumasite has been studied experimentally by means of a single crystal X-ray diffraction and FTIR methods, and theoretically using density functional theory (DFT) method. Very good agreement was achieved between calculated and experimental structural parameters. In addition, calculations offered the refinement of the positions of the hydrogen atoms. The detailed analysis of the hydrogen bonds existing in the thaumasite structure has been performed. Several types of hydrogen bonds have been classified. The water molecules coordinating Ca{sup 2+} cation act as proton donors in moderate O-H···O hydrogen bonds formed with CO₃⁻²and SO₄⁻² anions. The multiple O-H···O hydrogen bonds exist among water molecules themselves. Finally, relatively weak hydrogen bonds form water molecules with the OH groups from the coordination sphere of the Si(OH)₆⁻² anion. Further, calculated vibrational spectrum allowed complete assignment of all vibrational modes which are not available from the experimental spectrum that has a complex structure with overlapped bands, especially below 1500 cm⁻¹. Highlights: • The thaumasite structure was studied experimentally and using DFT method. • We used DFT method for the refinement of the positions of hydrogen atoms. • A detailed analysis of the hydrogen bonds was done. • A complete assignment of all bands tomore » particular types of vibrations was done.« less
Authors:
 [1] ; ;  [2] ;  [1] ;  [1] ;  [3]
  1. Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 36 Bratislava (Slovakia)
  2. Department of Physical Chemistry, Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, 812 37 Bratislava (Slovakia)
  3. (Austria)
Publication Date:
OSTI Identifier:
22323137
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 59; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANIONS; CATIONS; CRYSTAL STRUCTURE; DENSITY FUNCTIONAL METHOD; FOURIER TRANSFORMATION; HYDROGEN; INFRARED SPECTRA; MOLECULES; MONOCRYSTALS; PROTONS; SPECTROSCOPY; WATER; X-RAY DIFFRACTION