A compositional series is defined by end-member stoichiometric
phases and a non-stoichiometric range of compositions given
between the end-member compositions. Consider, for example,
the two solids
Al2O3 and
Cr2O3 as
end members. The compositional series in which 5 to 15% of
the Al atoms are replaced by Cr atoms, typically given in a
format like
(Al1-xCrx)2O3: 0.05 ≤ x ≤ 0.15,
is encoded as
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{*Al2O3}{sdemr={*Cr2O3},Al-Cr:0.05-0.15}
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The SSAM-based
annotation with marker sd
employs the dictionary key emr
to specify the second end member and the compositional range.
This key expects the SFN-based CurlySMILES notation of the
second end member. Range specification
is done by continuing with a comma followed by the
pair of exchanged atoms, followed by a colon, followed by
the values for the range boundaries. Within each pair, the
data are separated by a dash. The first atom of the pair
is the one in the annotated notation that is replaced by the
second atom of the pair to get the
notation of the second end member.
Multiple substitutions are possible. The series representation
(Mg1-xFex)2(SiO4)1-y(GeO4)y: 0.1 ≤ x ≤ 0.6 and 0 ≤ y ≤ 0.3
can be translated into the following CurlySMILES notation:
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{*Mg2(SiO4)}{sdemr={*Fe2(GeO4)},Mg-Fe:0.1-0.6, \
(SiO4)-(GeO4):0-0.3}
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Notice that range specification is optional. A notation without
range specification presents the whole range of a binary sytem
in terms of its end phases. Compositional series, encoded in the
format shown herein, may correspond to binary systems including
solid solutions, alloys and salt mixtures. However, no particular
atomic arrangement or structure is implied by the CurlySMILES
notations using the emr format,
unless additional annotation parameters do so.
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