Relationship of Copper Sulfide and Cadmium Sulfide Phases

Single-crystal CdS can be converted by cation exchange in CuCl solution to single-crystal copper sulfide with the chalcocite, djurletie, and CuxS (with 1.96>x>1.8) structures. The last is a previously undescribed hexagonal or pseudohexagonal phase with a=15.475±0.010 Å and c=13.356±0.010 Å. The structural relationship of the various phases to each other and to CdS is described with reference to two basic sulfur arrangements: hexagonal and cubic close packing. The gradual shift of phase of small crystals from high to lowered copper content is attributed to surface oxidation of copper atoms and strongly suggests that natural chalcocite crystals may also change composition and phase with time.