Distribution of the Pb and Sb atoms in the (Pb, Sb)S layers of the Franckeite-type misfit compound [(Pb, Sb)S](2.28)NbS2 examined by scanning tunneling and atomic force microscopy

The distribution of the Pb and Sh atoms in the (Pb, Sb)S layers of the misf it compound [(Pb, Sb)S](2.28)NbS2 was investigated by scanning tunneling mi croscopy (STM) and atomic force microscopy (AFM), This compound has NaCl-ty pe MS (M = Pb, Sb) layers (Q-layers) alternating with NbS2 layers (H-layers ) in which the Nh atoms are located in slightly distorted trigonal prism si tes. Both the H- and Q-layers of [(Pb,Sb)S](2.28)NbS2 were imaged by STM an d AFM. The atomic-scale STM and AFM images were analyzed in terms of the pa rtial and total electron density plots calculated for the Q- and H-layers, The STM images of the Q-layers allowed us to detect all the constitutive at oms of the Q-layers with a short-range ordering of pure Pb and Sb rows in t he a(Q) modulation direction. (C) 2000 Academic Press.