ROOM-TEMPERATURE CRYSTAL-STRUCTURE OF THE LAYERED PHASE CU(I)IN(III)P2S6

The room-temperature structure of CuInP2S6 was determined using single -crystal X-ray diffraction. It crystallizes in the monoclinic symmetry , space group Cc, with the lattice parameters a=6.0956(4) Angstrom, b= 10.5645(6) Angstrom, c=13.6230(8) Angstrom beta=107.101(3)degrees, V=8 38.5(1) Angstrom(3) and Z=4. As for CuCrP2S6 and CuVP2S6, the layered structure consists of a succession of ((SCu1/3In1/3III)-In-I(P-2)(1/3) S) slabs separated by empty van der Waals gaps. Within a slab, the oct ahedral voids defined by the ABC close-packed array of sulfur are fill ed by the metal cations and P-2 groups such that a triangular two-dime nsional sublattice is formed by each of them. The Cu(I) ions are distr ibuted on two inequivalent off-center sites with occupation ratios of about 0.9 and 0.1 per octahedron, and the In(III) ions are displaced f rom the center of their octahedra.