Understanding the Effect of Oxygen on M ₅ AX ₄ Structure, Stability, and Mechanical Properties

High Resolution Image Download MS PowerPoint Slide M 5 X 4, 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 M 5 AX 4 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 M 5 AX 4 compositions: Ti 2.5 Ta 2.5 AlC 4, Ti 2.675 Nb 2.325 AlC 4, and Mo 4 VAlC 4 . By modeling the structural stability of each composition, we investigate the possible stabilizing role of oxygen. To guide future application of M 5 X 4 MXenes, we also calculate the electronic structure and mechanical properties of the parent M 5 AX 4 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.