# Understanding the Effect of Oxygen on M5AX4 Structure, Stability, and Mechanical Properties

## TL;DR

This study explores how oxygen affects the structure and properties of M5AX4 materials, which are important for creating new nanomaterials.

## Contribution

The paper reveals how oxygen stabilizes M5AX4 MAX phases and influences their mechanical and electronic properties.

## Key findings

- Oxygen incorporation stabilizes M5AX4 MAX phases by forming oxycarbide layers.
- Electronic and mechanical properties of M5AX4 MAX phases were calculated for potential MXene applications.
- Layer-by-layer elemental analysis was conducted on three M5AX4 compositions.

## Abstract

M5X4, the newest and thickest structures
in the MXene family, shows promise as mechanically robust nanomaterials.
However, the essential role of oxide in their synthesis is poorly
understood, which poses a challenge for discovering new M5AX4 MAX phase precursors. One possibility is that oxygen
dissolves into the carbon sublattice, forming stable oxycarbide layers
within the MAX phase. Herein, we investigate the layer-by-layer elemental
composition of three M5AX4 compositions: Ti2.5Ta2.5AlC4, Ti2.675Nb2.325AlC4, and Mo4VAlC4. By
modeling the structural stability of each composition, we investigate
the possible stabilizing role of oxygen. To guide future application
of M5X4 MXenes, we also calculate the electronic
structure and mechanical properties of the parent M5AX4 MAX phases. This work clarifies the role of oxygen incorporation
into MAX phases and its implications for the synthesis and potential
applications of their MXene derivatives.