Chapter 6
Trends in Stability and
Bandgaps of Binary
Compounds in Different
Crystal Structures
6.1 Introduction
One of the simplest class of compounds are binary compounds which only
have two constituent elements and different crystal structures e.g wurtzite,
zinblende, rocksalt, NiAs and rutile. Often times, same compound exists in
different crystal structures under different conditions and different structures
may have significantly different properties. For example, the anatase phase of
TiO2 is found to be photo-catalytically active 83 where as the rutile phase
is not 114 even though both the structures are energetically very close with
rutile phase being slightly more stable than anatase phase 115. Additionally,
rocksalt structure of ZnO which is significantly lower in stability as compared
to the native wurtzite structure has been stabilized in MgO matrix 116, 117.
Thus, above studies suggest that compounds with different degree of metastability
can be synthesized and stabilized at normal conditions which motivated
us to explore different crystal structures of the same compound. In the current
work we explore four different crystal structures of the binary compounds in
AB stoichiometry where A and B are chosen from a set of 44 and 16 elements
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