Atomic and electronic structure of Mo₆S_9−xI_xnanowires

Abstract

Moybdenum-based subnanometre diameter nanowires are easy to synthesize and disperse, and they exhibit a variety of functional properties in which they are superior to other one-dimensional materials. However, further progress in the understanding of physical properties and the development of new and specific applications have so far been impeded by the fact that their structure was not accurately known. Here we report on a combination of systematic x-ray diffraction and extended x-ray absorption fine structure experiments, and first-principles theoretical structure calculations, which are used to determine the atomic skeletal structure of individual Mo6S9−xIx (MoSIx) nanowires, their packing arrangement within bundles and their electronic band structure. From this work we conclude that the variations in functional properties appear to arise from different stoichiometry, not skeletal structure. A supplementary data file is available from http://stacks.iop.org/0957-4484/16/1578

Dispersion and purification of Mo6S3I6 nanowires in organic solvents

“…Such a feature has also been observed for Mo 6 S 4.5 I 4.5 nanowires. 8 The position of this peak agrees well with predictions for the MoSI band gap 12 suggesting that it may represent a transition involving the van Hove singularity associated with the band edge. All these features are visible in the washed Mo 6 S 3 I 6 sample, which should be a combination of these three phases, as was expected, although the peak at 0.64 eV is quite weak due to the high intensity of the near infrared peaks in sediment 1.…”

“…11 The stoichiometries synthesized so far are Mo 6 S 3 I 6 , 5 Mo 6 S 4.5 I 4.5 , 8 and Mo 6 S 2 I 8 , all of which have excellent mechanical and electrical properties. Local density approximation band structure calculations of the Mo 6 S 3 I 6 nanowire predict it to be semimetallic, 12 and Ohmic behavior of this stoichiometry has been observed. 13 The Mo 6 S 2 I 8 stoichiometry has been reported to be metallic, 14 while the Mo 6 S 4.5 I 4.5 nanowire electronic structure has not yet been reported.…”

First principles study of electronic and mechanical properties of molybdenum selenide type nanowires

“…20,21 Recently, Mo 6 S 9−x I x wires have been synthesized. 22 The structure of these wires consists of a rigid Mo octahedra. Each Mo atom is decorated with S or I atoms and octahedras are again connected by three S or I atoms.…”

Observation of van der Waals Driven Self‐Assembly of MoSI Nanowires into a Low‐Symmetry Structure Using Aberration‐Corrected Electron Microscopy

“…These wires are conductive [5] and all have identical electronic properties. [6] In addition, they can easily be dispersed in common solvents [7,8] down to individual nanowires. [5,9] These materials have already displayed promise as field-emission tips [10] and in nanotribological applications.…”

“…A number of studies based on X-ray diffraction (XRD) have resulted in only moderate success. [6,12] Although this is partly caused by low sample purity, XRD studies on nanoscale systems are generally problematic because of the presence of diffuse components caused by the lack of long range order. To overcome this problem, both extended X-ray-absorption finestructure [6] (EXAFS) and XRD measurements incorporating atomic pair-distribution-function [12] (PDF) analysis have been carried out to determine the average local structure.…”