The following is an example of typical studies of Cu-Te-Sb-S Phase systems.
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Experimental studies of the phase systems Cu-Te-Sb and Cu-Te-S at
temperatures between 350 and 1000 °C have shown the existence of a
previously undescribed Cu rich phase. The phase is stable at temperatures
between 400 and 900 °C. The crystal structure of this phase, Cu9.1TeSb3 was determined from X-ray diffractometer data.
Tellerium is 12-coordinated by Cu (with 3/4 occupancy) at the distance of 2.614
å. The Cu polyhedron is an icosahedron with four of its ten ideal 3 axes
situated in the direction of cubic 3 axes and three of its ideal twofold axes.
The copper polyhedron around Sb is a distorted cubooctahedron.
The crystal structure of Cu9.1TeSb3 is a stuffed derivative
of the Cr3Si-structure. The central Te atoms correspond to Si, the Sb icosahedra
to those of Cr. The atomic coordinations and the chemical formula of Cu9.1TeSb
3 show that it has character of intermetallic compound.
For copper coordination
the formation of (Cu0.5)12Te clusters appears more important than the
accomodation of Cu-Sb distances: The coppper coordination is not a dual (pentagonal dodecahedron)
to the enveloping icosahedron.
The figures show the structure of the described phase and the
shape of the mentioned icosahedron.