Phase behaviour of (Ti:Mo)S$_2$ binary alloys arising from electron-lattice coupling

TL;DR

This study uses electronic structure calculations and statistical mechanics to predict phase separation in (Ti:Mo)S$_2$ alloys, aligning with experimental data and shedding light on their phase behaviour relevant for tribology applications.

Contribution

It introduces a computational approach combining electronic structure and statistical mechanics to understand phase behaviour in TMD alloys, specifically (Ti:Mo)S$_2$.

Findings

Predicted phase-separating behaviour in (Ti:Mo)S$_2$ alloys.

Solubility limits as a function of temperature match experimental data.

Identified the origin of phase behaviour in d-band energetics due to crystal field splitting.

Abstract

While 2D materials attract considerable interests for their exotic electronic and mechanical properties, their phase behaviour is still largely not understood. This work focuses on (Mo:Ti)S$_2$ binary alloys which have captured the interest of the tribology community for their good performance in solid lubrication applications and whose chemistry and crystallography is still debated. Using electronic structures calculations and statistical mechanics we predict a phase-separating behaviour for the system and trace its origin to the energetics of the $d$-band manifold due to crystal field splitting. Our predicted solubility limits as a function of temperature are in accordance with experimental data and demonstrate the utility of this protocol in understanding and designing TMD alloys.