Nanotubes From Chalcogenide Misfit Compounds

Gal Radovsky, Materials and Interfaces, WIS, Rehovot, Israel
Ronit Popovitz-Biro, Chemical Research Support, WIS, Rehovot, Israel
Reshef Tenne, Materials and Interfaces, WIS, Rehovot, Israel

Metal-chalcogenides misfit layered compounds (MLC) of the general formula (MX)1+yTX2, (T=Sn,Ti,V,Cr,Nb,Ta; M=Sn,Pb,Bi,Sb, rare earths; X=S,Se) consist of a superstructure of alternating layers. The MX is a two atom thick {001} slice of orthorhombic distorted NaCl structure. TX2 is a three atom thick pseudo-hexagonal sandwich layer in which the metal T is surrounded by six chalcogen atoms. Each sublattice has two a and b in-plane lattice-parameters. A misfit in the ab plane of the two sublattices may lead to relaxation through scrolling. This driving force in addition to the annihilation of the dangling bonds in the (hk0) rims of the layers, leads to a new kinds of nanotubes from MLC. Tubular structures from the  SnS-SnS2,[1-3], PbS-NbS2 [3] ,MS-TaS2 [4] with (M=Sn,Pb,Sb,Bi) and very recently LaS-TaS2[5] MLC were synthesized. The in-plane incommensurate behavior between the MX and the TX2 has a large influence on the internal structures of the nanotubes. High resolution transmission electron microscopy (HRTEM) equipped with energy dispersive X-ray spectroscopy (EDS), selected area electron diffraction (SAED) analyses scanning electron microscopy (SEM), scanning-transmission electron microscopy (STEM) are used here to decipher the complex structures of these nanotubes. The possibility to use the two kinds of folding mechanisms jointly, offers a new apparatus for the synthesis of unique 1-D nanostructures with great complexity and with potentially large diversity of physio-chemical properties.

1. G. Radovsky, R. Popovitz-Biro, M. Staiger, K. Gartsman, C. Thomsen, T. Lorenz, G. Seifert, R. Tenne, Angew. Chem, Intl. Ed. 50, 12316-12320, (2011).

2. G. Radovsky, R. Popovitz-Biro, R. Tenne, Chem. Mater. 24, 3004-3015, (2012).

3. G. Radovsky, R. Popovitz-Biro, D. G. Stroppa, L. Houben and R. Tenne, Acc. Chem. Res, 47, 406-416, (2014).

4. G. Radovsky, R. Popovitz-Biro, and Reshef Tenne, Chem. Mater., 26, 3757-3770, (2014).

5. L. S. Panchakarla, G. Radovsky, L. Houben, R. Popovitz-Biro, R. E. Dunin-Borkowski and R. Tenne,  J. Phys. Chem. Lett., 5, 3724−3736, (2014).

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