Ivor and Olive Lewis on fri 17 dec 04
Dear Richard Mahaffey,
You are wise to suggest caution before drawing conclusions.
If images of the two dimensional model of Silica Glass, as shown in
Lawrence and West, "Ceramic Science for the Potter" p9, Fig 1-4, are
examined and extrapolated, via imagination, into a three dimensional
model two things become clear
1. The molecular framework of silica-oxygen tetrahedra will be rigid,
even more rigid than a crystal lattice.
2. The structure, both in the short range and the long range, will
always be under stress due to the distortion or non alignment of
Oxygen bridging bonds.
Given the degree of structural stress and the high rigidity, the
imposition of additional stress will be more likely to cause fracture
than flow. Flow would necessitate wholesale breaking of
Silicon-Oxygen-Silicon bonds.
The Zachariasen Model seems to be universally accepted but it is only
one of several models of the glassy condition, non of which can
account for the rejection of and instability of copper oxide as a
network modifier.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
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