Growth and Characterization of One-Dimensional SnTe Crystals within the Single-Walled Carbon Nanotube Channels

Quasi-free-standing one-dimensional (1D) SnTe crystals were grown within the channels of single-walled carbon nanotubes (SWCNTs) from the melt using the capillary technique. The crystal structure of the 1D SnTe crystal was determined from transmission electron microscopy measurements and density functional theory calculations. The obtained structure for the 1D crystal—(SnTe)5n—shows in comparison to the bulk structure a significant bond length relaxation (contraction) along the SWCNT axis, which is accompanied by a decrease of the Sn and Te effective charges. In contrast to bulk rocksalt SnTe and 1D (SnTe)4n crystal as well, the (SnTe)5n crystal shows the gapless band structure due to the contribution of orbitals mostly composed by three-coordinated atoms. X-ray photoelectron spectroscopy and Raman spectroscopy data indicate that there are no noticeable interactions between the 1D SnTe crystal and the SWCNTs other than a minor donor influence on the electron structure of metallic SWCNTs; this influence is in line with gapless state of (SnTe)5n.