Effect of Temperature and Oxygen Partial Pressure on Coordination and Valence States of Fe Cations in Calcium Silicate Glasses: A Mössbauer Study

  • R. A. Levy

Abstract

Current models of silicate liquids are generally discussed from a structural standpoint in terms of an irregular assemblage of O2− anions in which the cations are distributed over the available cavities. In these models, it is generally considered that “network-formers”, such as the Si4+ cations, occupy tetrahedral sites while “network-modifiers” such as the Ca2+, Fe2+ or Na+ cations occupy octahedral sites. Amphoteric cations such as Fe3+ of Al3+ can occupy both positions. In a study of a wide range of sodium and calcium silicate glasses Pargamin et al.1 and Levy et al.2 reported on the usefulness of the Mössbauer effect in determining simultaneously the valence states and coordination of Fe cations present as a major constituent in these amorphous systems. In a continuing effort to provide a more complete basis for understanding the structure of oxide glasses, we consider in this Mössbauer study the effect of equilibration temperature and oxygen partial pressure on the distribution of Fe cations between valences and coordination sites in two calcium silicate glasses. The nominal compositions of the samples (expressed in weight per cent) are as follows:
$$ {\text{Group}}\;{\text{I}}\;\;\;\;\;\;\;{\left[ {{{({\text{Si}}{{\text{O}}_2})}_{65}}{{({\text{CaO)}}}_{35}}} \right]_{65}}{\left[ {{\text{F}}{{\text{e}}_2}{{\text{O}}_3}} \right]_{35}} $$
These samples were equilibrated in an atmosphere of air at 1350°C, 1391°C, 1436°, 1503°, 1550° and 1569°.

Keywords

Furnace Zirconia Silicate Boron Nitride 

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References

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Copyright information

© Plenum Press, New York 1977

Authors and Affiliations

  • R. A. Levy
    • 1
  1. 1.Rensselaer Polytechnic InstituteTroyUSA

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