Preparation and crystal structure of the Ni7Si2P5 phosphide

New ternary phosphide Ni7Si2P5 has been synthesized by direct interaction b etween powders of pure components at 1070 K and its crystal structure has b een determined using X-ray single crystal method. The structure is of a new type with space group Pbcn (no. 60) and lattice constants as follows, a = 23.84(2) Angstrom, b = 5.925(2) Angstrom, c = 4.922(1) Angstrom, Z = 4. The final residuals are R-F = 0.048, R-w = 0.044 for 362 symmetry independent reflections (diffractometer KM-4, MoKalpha-radiation). Crystal structure of Ni7Si2P5 is closely related to Ni2SiP and Ni5Si2P3 structures which belong to the series of linear inhomogeneous structures M2m+2nX2m+2n (M and X cor respond to metal and non-metal atoms, respectively) and are derivatives fro m the MnP-type structure.