A study of the system Yb + S, mainly by electron diffraction/microscopy

An electron diffraction study of various ytterbium sulfide preparations reveals the presence of several phases: “Yb 3S 4” in two orthorhombic forms, Ccmm at high temperatures and Pnma, the latter sometimes incommensurately modulated, sometimes not; B1-related types, both cubic and rhombohedral, again the latter sometimes incommensurately modulated. The results are generally consistent with those previously reported. They reveal the absence of long-range order in some of the B1-related phases, and the consequent difficulty in identifying and delineating the phase relations between the cubic and rhombohedral Yb 1−δS types.