HIGH-RESOLUTION TRANSMISSION ELECTRON-MICROSCOPY OF HEXAGONAL AND RHOMBOHEDRAL MOLYBDENUM-DISULFIDE CRYSTALS

Natural (molybdenite) and synthesized molybdenum disulfide crystals have been studied by high-resolution transmission electron microscopy. The image simulation demonstrates that the [0001] and [0110BAR] HRTEM images of hexagonal and rhombohedral MoS2 crystals hardly disclose their stacking sequences, and that the [2110BAR] images can distinguish the Mo and S columns along the incident electron beam and enable one to determine not only the crystal structure but also the fault structure. Observed [0001] images of cleaved molybdenite and synthesized MoS2 crystals, however, reveal the strain field around partial dislocations limiting an extended dislocation. A cross-sectional image of a single molecular (S-Mo-S) layer cleaved from molybdenite has been observed. Synthesized MoS, flakes which were prepared by grinding have been found to be rhombohedral crystals containing many stacking faults caused by glides between S/S layers.