Chemistry Reference
In-Depth Information
6 Conclusions
We set out to exploit the new data contained in [
13
] to search for possible
substructures within the three reported modifications of the compound Li
7
VN
4
,
and this we have done. We have also attempted a chemical rationalization for these
substructures. It now seems obvious that all these interrelationships are implicit in
the parent fluorite-type (or anti-fluorite-type) structures.
If we return to the question posed early in this discussion as to “What is a crystal
structure”, we now take the view, as quoted earlier, “from the purely crystallo-
graphic perspective, a structure is simply a set of occupied sites pertaining to the
underlying symmetry of a particular space group, regardless of the chemical
nature of the occupancy”.
However, the structural relationships, we have described in this work, clearly
indicate that these are not merely a geometrical result, but they have chemical sense
as revealed by the Zintl-Klemm concept. In this regard, the maintenance of the
pseudo-structures of nitrogen, described in Sects. 3.1.1 and 4.1.1, is paradigmatic.
On the other hand, what prompted this investigation was the recent publication
of International Tables of Crystallography, Vol. A1 [
13
], without which it would
not have been possible for us to proceed. The very detailed information relating to
groups and subgroups contained therein is probably not common knowledge, and
accordingly, we express our admiration and thanks to its editors and contributors.
Acknowledgement D.J.M.B and R.L.M put on record their immense gratitude to their respective
daughters, Hilary and Lisa, for their help in this work.
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