Stacking faults in WS2 and WS1.8 single crystals

Single crystals of WS2 and off-stoichiometric WS2 (i.e.WS1.8) have been grown by a direct vapour transport technique. The crystals have been characterized by X-ray studies for structure determination. The particle size for a number of reflections has been calculated using Scherrer's formula. A realistic estimation of growth and deformation fault probabilities has been made in both WS2 and WS1.8 crystals. It is seen that off-stoichiometry leads to an increase in the number of stacking faults. The presence of stacking faults in the tungstenite crystals has been confirmed from weak-beam electron microscopy of the thin samples obtained from these crystals.