Designing Hydrogen Permeation Barriers in Titanium Aluminium Nitride through First Principles Density Functional Theory Calculations

TL;DR

This study uses first principles DFT calculations to analyze hydrogen permeation in TiAlN, revealing its high resistance to hydrogen absorption and migration, influenced mainly by crystallographic structure, making it suitable for hydrogen-related high-pressure applications.

Contribution

It provides detailed atomic-level insights into hydrogen absorption and migration in TiAlN, emphasizing the importance of crystal structure over composition in designing hydrogen-resistant materials.

Findings

Hydrogen absorption in TiAlN is highly endothermic with low uptake probability at ambient conditions.

Hydrogen migration barriers are high, especially in hexagonal structures, indicating low diffusion rates.

Crystallographic structure significantly influences hydrogen permeation resistance.

Abstract

This study investigates hydrogen permeation in titanium aluminium nitride (TiAlN) using ab initio density functional theory (DFT) for cubic and hexagonal crystal structures. Despite the significance of hydrogen barriers, the potential of TiAlN has not been fully explored. We analyzed site specificity, temperature-dependent insertion, and atomic hydrogen migration path energies. Our research highlights the decisive role of crystallographic structure over chemical composition in designing materials resistant to hydrogen absorption. However, once absorbed, hydrogen diffusion is governed by the local chemical environment. Specifically, hydrogen migration through an Al-N plane requires more energy than through Ti-N, which affects the overall diffusion process. We found hydrogen absorption is highly endothermic, with insertion energies from 50 to 320 kJ/mol of hydrogen atom, indicating low uptake probability at ambient conditions. Higher temperatures further increase the energy required, making absorption less favourable. We also identified substantial energy barriers for hydrogen migration, particularly in the hexagonal structure, with peaks up to 276 kJ/mol, indicating a very low probability of migration. These findings underscore the exceptional resistance of TiAlN to hydrogen permeation, making it a promising candidate for high-pressure applications such as hydrogen storage and nuclear reactors.