Room-temperature crystal structure of the layered phase CuIInIIIP2S6

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) Å, b = 10.5645(6) Å, c = 13.6230(8) Å, β = 107.101(3)°, V = 838.5(1) Å and Z = 4. As for CuCrP2S6 and CuVP2S6, the layered structure consists of a succession of (SCuI13InIII13(P2)13S) slabs separated by empty van der Waals gaps. Within a slab, the octahedral voids defined by the ABC close-packed array of sulfur are filled by the metal cations and P2 groups such that a triangular two-dimensional sublattice is formed by each of them. The Cu(I) ions are distributed 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 from the center of their octahedra.