  The structure of MX3 transition metal trichalcogenides (TMTs, with M a
transition metal and X a chalcogen) is typified by one-dimensional (1D) chains
weakly bound together via van der Waals interactions. This structural motif is
common across a range of M and X atoms (e.g. NbSe3, HfTe3, TaS3), but not all M
and X combinations are stable. We report here that three new members of the MX3
family which are not stable in bulk, specifically NbTe3, VTe3, and TiTe3, can
be synthesized in the few- to single-chain limit via nano-confined growth
within the stabilizing cavity of multi-walled carbon nanotubes. Transmission
electron microscopy (TEM) and atomic-resolution scanning transmission electron
microscopy (STEM) reveal the chain-like nature and the detailed atomic
structure. The synthesized materials exhibit behavior unique to few-chain
quasi-1D structures, such as multi-chain spiraling and a trigonal
anti-prismatic rocking distortion in the single-chain limit. Density functional
theory (DFT) calculations provide insight into the crystal structure and
stability of the materials, as well as their electronic structure.
