Structure of IIIa-ZnIn2S4 under High Pressure

The only member of the II–III2–VI4 semiconductor family with layered structure is ZnIn2S4. At ambient conditions several polytypes of this compound have been reported. Energy dispersive X-ray diffraction of ZnIn2S4 has been realized at high pressure up to 18 GPa. The structure of this polytype IIIa-ZnIn2S4 is rhombohedral with space group R3-m. It consists of a close-packed arrangement of S atoms, with Zn and half of the In atoms randomly distributed on tetrahedral sites, and the other half of the In atoms located on octahedral sites. The hexagonal axes are a = (3.873 ± 0.002) A and c = (37.067 ± 0.004) A (V = 482 A3, 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.