Neutron Rietveld refinement of the structure of the ternary silicide Ti4Ni4Si7

Abstract

The structure of Ti4Ni4Si7 is studied using powder neutron diffraction and Rietveld analysis. Prccise determination of the crystalline parameters, atomic positions, and temperature factors is achieved. A criterion previously elaborated for the phase TiFeSi2 is used to determine the coordination number. From the arrangement of the atoms in the unit cell and their interbond distances, we find that Si atoms are nearest neighbors to Ti and Ni. An extension of the same criterion shows that Ti–Ni and Ni–Si hybridization is likely to be strong while Ti–Ni hybridization is weak. A comparison with mono- and disilicides is made.