The only member of the II-III2-VI4 semiconductor family with layered struct
ure is ZnIn2S4. At ambient conditions several polytypes of this compound ha
ve been reported. Energy dispersive X-ray diffraction of ZnIn2S4 has been r
ealized at high pressure up to 18 GPa. The structure of this polytype IIIa-
ZnIn2S4 is rhombohedral with space group R (3) over bar m. It consists of a
close-packed arrangement of S atoms, with Zn and half of the In atoms rand
omly distributed on tetrahedral sites, and the other half of the In atoms l
ocated on octahedral sites. The hexagonal axes are a = (3.873 +/- 0.002) An
gstrom and c = (37.067 +/- 0.004) Angstrom (V = 482 Angstrom(3), Z = 3). NO
phase transition has been observed between 0 and 18 GPa. The bulk modulus,
obtained by fitting the data to a first-order Murnaghan equation of state
is B = (82 +/- 8) GPa.