Modeling the Structure of Amorphous MoS₃:  A Neutron Diffraction and Reverse Monte Carlo Study

Abstract

A model for the structure of amorphous molybdenum trisulfide, a-MoS3, has been created using reverse Monte Carlo methods. This model, which consists of chains of MoS6 units sharing three sulfurs with each of its two neighbors and forming alternate long, nonbonded, and short, bonded, Mo-Mo separations, is a good fit to the neutron diffraction data and is chemically and physically realistic. The paper identifies the limitations of previous models based on Mo3 triangular clusters in accounting for the available experimental data.

Synthesis of tungsten sulfide nanoparticles and their tribological properties as additives for lubricating oils

“…Thus, X-ray fluorescence analysis definitely evidences that the thermal decomposition of tetrathiotungstates under rather mild conditions (temperatures no higher than 160°C) and an inert atmosphere leads to the formation of tungsten trisulfide, which accords well with the data for molybdenum trisulfide nanoparticles we obtained previously [23]. As for the extrastoichiometric S/W atomic ratio (3.8 on average), this result can be related to the presence of -S-S-bridges in the tungsten trisulfide structure, which are presented in amorphous Mo and W trisulfides, as was shown in [30]. The results of size determination of tungsten trisulfide nanoparticles performed by dynamic light scattering are presented in Fig.…”

Metallic and highly conducting two-dimensional atomic arrays of sulfur enabled by molybdenum disulfide nanotemplate

“…1c. The vertical distance between S1 and S2 atom determined from structure optimization is around 0.31 nm, which is much longer than the typical S-S covalent bond length (around 0.2 nm), 12 suggesting a non-bonded interaction type between S1 and S2 atom. Charge analysis suggests that in the current configuration S1 atom has a small negative charge of −0.015 e j j, while −0.092 e j j for atom S2, −0.102 e j j for atom S3 and 0.209 e j j for atom Mo (Supplementary Figure 2).…”

Influence of temperature and ZDDP concentration on tribochemistry of surface-capped molybdenum sulfide nanoparticles studied by XANES spectroscopy

“…The use of nanoparticle material in our case presents better conditions for self-organization of molybdenum sulfide molecules into the nanocrystalline network. In fact, the nano-MoS 3 core having the diameter of about 15 nm contains up to 15,000 MoS 3 molecules (or 5,000 Mo 3 S 9 clusters) in one nanoparticle (assuming the atomic density of 0.0389 atoms/Å for the molybdenum trisulfide model [13]). At the same time, the molecularbased additive such as MoDTC, upon decomposition, produces only a few MoS 2 -type fragments in close proximity, and it requires the additional step of molecular self-association to produce a large MoS 2 sheet.…”

“…These considerations lead to the conclusion that tribofilms are composed mainly of zinc phosphate glass incorporating some zinc polyphosphate chains. In addition, zinc is also present in the form of zinc sulfide, while molybdenum is in the form of Mo(IV) sulfideseither MoS 3 (which is better described by the MoS(S 2 ) formula [13]) or MoS 2 . Temperature increases the growth of the phosphate-type tribofilm, while relative content of Mo(S)-type components decreases.…”