The incommensurate misfit layer structure of (SnS)1.17NbS2, 'SnNbS3'. Pt. 1

(SnS)1.17NbS2, Mr = 334.92, is a compound with misfit layer structure consiting of two-atom-thick layers of SnS and three-atom-thick sandwiches of NbS2 which alternate along the c axis. The lattices of SnS and NbS2 both have C-centered orthorhombic unit cells which match along the b and c axes but not along the a axes. The unit cells and space groups are a = 5.673(1), b = 5.750(1), c = 11.760(1) A, space group C2mb (no.39), Z = 4, for SnS; a = 3.321(1), b = 5.752(1), c = 11.763(1) A, space group Cm2m (no.38), Z = 2, for NbS2. From the ratio of the lengths of the a axes of the two parts of the complete structure (5.673/3.321 = 1.708 being irrational) one obtains a composition (SnS)1.17NbS2. The structure determination consisted of three parts: the structures of the SnS and NbS2 parts separately and their relative position. (orig./BHO)