Molybdenum and Niobium Sulphides

TL;DR: In this article, a CdCl2-type structure was proposed for the disulphide MoS2 in space-group R3m-C67656763ν : 3 Mo situated in 3(a) ; 0 0 z, etc., with z=0 ; 3 S I in 3 (a) with z≈¼ and 3 S II in 3

Abstract: IN the system Mo-S the only compound that is formed by direct synthesis from the elements is the disulphide MoS2. This compound exists in two modifications : (1) The well-known hexagonal form (a=3.16 ; c=12.29 A.), the structure of which1 is shown in Fig. 1a. (2) The rhombohedral form (a=3.17 ; c=18.38 A.) which was first described by Bell and Herfert2. These authors propose a CdCl2-type structure which, however, is incompatible with their own and our X-ray diffraction data. Good agreement is found for the structure shown in Fig. 1b. This structure can be described in space-group R3m—C 5 3ν : 3 Mo situated in 3(a) ; 0 0 z, etc., with z=0 ; 3 S I in 3(a) with z≈¼ and 3 S II in 3(a) with z≈5/12.