| Abstract Scope |
MoS2 can be used as a solid lubricant for space. Preliminary studies suggest doping with Ni can reduce friction and wear, but the structure and mechanisms remain unclear [MR Vazirisereshk, A Martini, DA Strubbe, and MZ Baykara, Lubricants 7, 57 (2019)]. We use density functional theory (DFT) to study bulk and monolayer Ni-doped MoS2, in various polytypes and doping levels. We consider formation energies for Mo or S substitution, intercalation, or adsorption, to build up a phase diagram, and predict stable phases or phase segregation. We compute corresponding Raman spectra to enable experimental identification. We additionally calculate elastic properties and potential energy for sliding to connect to atomic-force microscopy friction experiments, and use our data to parametrize classical force fields for molecular dynamics that can directly address friction and wear on larger length and time scales, and reveal mechanisms of tribological performance. |