First principles study of oxidation of Si segregated {\alpha}-Ti(0001) surfaces

TL;DR

This study uses density functional theory to investigate how silicon segregation on Ti(0001) surfaces affects oxidation, showing that Si reduces oxygen dissolution and increases diffusion barriers, potentially enhancing corrosion resistance.

Contribution

It provides a first-principles analysis of Si segregation effects on Ti(0001) oxidation, revealing mechanisms that could improve oxidation resistance.

Findings

Si prefers to segregate at the surface layer of Ti(0001).

Si segregation increases the oxygen diffusion barrier.

Si reduces the binding of oxygen to Ti(0001).

Abstract

The oxidation of {\alpha}-Ti(0001) surface was studied using density functional theory. In order to enhance the oxidation resistance, we substituted Ti atoms with Si atoms in Ti(0001) surface. We observe that Si prefers to segregate at the surface layer of Ti(0001) compared to other sub-surface layers. The Si solubility on the Ti(0001) surface was estimated to be around 75 at.%. While Si segregation was found to reduce the binding between the oxygen atom and the Ti(0001) surface, the barrier for oxygen to diffuse into the slab increases. The dissociation of the oxygen molecule on the clean and Si segregated surfaces of Ti was found to be barrier-less. Overall, the Si segregation on the Ti(0001) surface was found to hinder the dissolution of oxygen in Ti.