Site preference of chalcogen atoms in 1T$^\prime$ $MX_{2(1-x)}Y_{2x}$ ($M=$ Mo and W; $X, Y=$ S, Se, and Te)

TL;DR

This study uses first-principles calculations to analyze how chalcogen atoms prefer specific sites in 1T' phase transition metal dichalcogenides, revealing their influence on structural and elastic properties.

Contribution

It provides a detailed understanding of chalcogen site preferences in $MX_{2(1-x)}Y_{2x}$ systems and links these preferences to structural stability and elastic behavior.

Findings

Chalcogen site preference explains the correlation between formation energy and Peierls distortion.

Site preference significantly affects linear elastic properties.

Impact on non-linear elastic properties is minimal.

Abstract

The insulator-metal transition, accompanying the structural phase transition from 2H to 1T$^\prime$ structure, has been reported in two-dimensional W-S-Te and W-Se-Te systems. It is also reported that Te atoms tend to occupy a specific site of the 1T$^\prime$ structure. Here, we study the site preference of chalcogen atoms in $MX_{2(1-x)}Y_{2x}$ ($M=$ Mo and W; $X, Y=$ S, Se, and Te; $0\le x \le 1$) using first-principles approach. We demonstrate that the site preference of chalcogen atoms explains the universal correlation between the formation energy and the Peierls-like distortion amplitude in the 1T$^\prime$ phase. The impact of the site preference on the linear elastic properties is strong, whereas its impact is weak in the non-linear regime. This establishes the structure-property relationships in $MX_{2(1-x)}Y_{2x}$ systems.