The crystal structure of the Pmmn phase of NiSi, as determined by X-ray powder diffraction. (a) A projection down . (b) A projection down . (c) The coordination polyhedron surrounding an Ni atom. The Si atoms are represented by small dark spheres. The symbols used are chosen to correspond to those used by Vočadlo et al. (2012) and their size is not intended to give a representation of the atomic displacement parameters.