Comparison of Orientations of OH-Bonds in Layer Silicates by Diffraction Methods and Electrostatic Calculations

Abstract

Abstract--Orientations of OH-vectors in structural hydroxyl groups of layer silicates were defined both from diffraction data and calculations of electrostatic energy. The comparison of the results showed that for the hydroxyls of the 2:1 layers of chlorites and micas the positions of the hydroxyl protons are mainly determined by electrostatics. For the hydroxyls of dickite, amesite, and the brucitic sheets of chlorite, the results derived by the two methods differed systematically from each other, pointing to a change in the nature of the bond in these OH-groups.

Interpretation of Mössbauer Spectra of Nontronite, Celadonite, and Glauconite

“…If the effective charges are proportional to ionic charges however, with about the same coefficient for all kinds of atoms, calculations may be carried out in terms of the ionic point-charge model. The choice of this model is also justified by the reasonable agreement between experimental O-H vector orientations and those calculated in the point-charge approximation (Bookin et al, 1982). 4.…”

Hydrogen Positions in Dickite

“…Significant discrepancies exist, however, between their refined hydrogen positions and those obtained from the calculations of Giese and Datta (1973). In addition, Rozdestvenskaya et al (1982) refined the structure of dickite from X-ray diffraction data and found the hydrogen coordinates to be at variance with the theoretical calculations of both Giese and Datta (1973) and Bookin et al (1982) and with the neutron values of Adams and Hewat (1981).…”

Electron Diffraction and High-Resolution Electron Microscopy of Mineral Structures

“…The O-H vector orientations in the micas under study obtained from OTED data have been compared with those yielded by electrostatic energy calculations (Bookin et al 1982). The differences in the corresponding angular parameters do not exceed 1 ° -2° .…”