Computational Study of Hydrogen Permeation Barriers in Titanium Aluminium Nitride

Kernekoncepter

Titanium aluminium nitride (TiAlN) exhibits exceptional resistance to hydrogen permeation, making it a promising candidate for hydrogen storage and nuclear applications.

Resumé

This study investigates the hydrogen permeation properties of titanium aluminium nitride (TiAlN) in cubic and hexagonal structures using density functional theory (DFT) calculations. The key findings are:

Hydrogen absorption into TiAlN is a highly endothermic process, with insertion energies ranging from 50 to 320 kJ/mol. This indicates a low likelihood of hydrogen uptake under ambient conditions.

The temperature-dependent analysis shows that higher temperatures increase the energy required for hydrogen incorporation, further reducing the probability of hydrogen absorption.

Migration path analyses reveal significant energy barriers for hydrogen diffusion in both cubic and hexagonal TiAlN structures. The cubic (010) plane exhibits the highest barrier at 118 kJ/mol, while the (100) and (001) planes have lower but still substantial barriers.

The hexagonal structure presents even higher migration barriers, with peaks up to 276 kJ/mol, underscoring the exceptional resistance of this polymorph to hydrogen permeation.

These findings demonstrate that TiAlN, in both its cubic and hexagonal forms, is a promising material for hydrogen permeation barriers, particularly suitable for applications in hydrogen storage systems and nuclear reactors where preventing hydrogen ingress is crucial.

Statistik

The insertion energy for hydrogen in cubic TiAlN is 222.88 kJ/mol.
The insertion energy for hydrogen in hexagonal TiAlN ranges from 50 to 320 kJ/mol, depending on the specific void site.
The highest migration energy barrier in cubic TiAlN is 118 kJ/mol, occurring between voids 7 and 8.
The highest migration energy barrier in hexagonal TiAlN is 276 kJ/mol, occurring between voids 19 and 17.

Citater

"The high insertion energies calculated for both structures indicate a solid resistance to hydrogen uptake, which is crucial for preventing hydrogen permeation and, thus, embrittlement in materials used for hydrogen storage and transportation."
"The substantial energy barriers for hydrogen migration observed in the hexagonal structure underscore the potential of TiAlN as a robust hydrogen permeation barrier, particularly relevant for high-pressure hydrogen environments, such as in hydrogen fuel storage tanks and reactors, where the prevention of hydrogen diffusion is essential for maintaining system safety and longevity."

Vigtigste indsigter udtrukket fra

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

by Cem ... kl. arxiv.org 10-03-2024

https://arxiv.org/pdf/2410.01301.pdf

Dybere Forespørgsler

How could the introduction of defects, such as vacancies or dopants, influence the hydrogen permeation properties of TiAlN?

The introduction of defects, such as vacancies or dopants, can significantly alter the hydrogen permeation properties of titanium aluminium nitride (TiAlN) by modifying the material's electronic structure and creating new pathways for hydrogen migration. Defects like nitrogen vacancies can serve as trap sites for hydrogen atoms, potentially lowering the energy barriers for hydrogen absorption and diffusion. This can lead to increased hydrogen uptake, which may compromise the material's integrity and lead to hydrogen embrittlement.
Dopants can also play a crucial role in influencing hydrogen behavior within TiAlN. By altering the local chemical environment, dopants can change the formation energies of defects and modify the electronic states within the band gap. This can enhance or inhibit hydrogen diffusion depending on the nature of the dopant and its interaction with the TiAlN lattice. For instance, certain dopants may stabilize specific defect configurations that facilitate hydrogen migration, while others may create additional energy barriers.
Overall, the interplay between defects and dopants in TiAlN can lead to a complex landscape of hydrogen permeation properties, necessitating careful consideration in the design of hydrogen barrier materials for applications in the hydrogen economy and nuclear industry.

What experimental techniques could be used to validate the computational findings and further investigate the hydrogen-TiAlN interactions?

To validate the computational findings regarding hydrogen permeation in TiAlN and to further investigate the interactions between hydrogen and TiAlN, several experimental techniques can be employed:

Electrolytic Hydrogen Permeation Testing: This technique involves measuring the rate of hydrogen permeation through TiAlN coatings under controlled electrochemical conditions. By applying a potential difference, hydrogen can be introduced on one side of the sample, and the permeation rate can be quantified on the opposite side, providing direct insights into the barrier properties of the material.

Thermogravimetric Analysis (TGA): TGA can be used to assess the hydrogen uptake capacity of TiAlN coatings at various temperatures. By monitoring weight changes as a function of temperature in a hydrogen atmosphere, researchers can determine the thermodynamic stability and absorption characteristics of the material.

X-ray Diffraction (XRD): XRD can be employed to analyze the structural changes in TiAlN upon hydrogen exposure. This technique can help identify phase transformations, such as the formation of hydrides or changes in crystallographic structure, which may occur due to hydrogen interaction.

Secondary Ion Mass Spectrometry (SIMS): SIMS can be utilized to profile the distribution of hydrogen within the TiAlN matrix. This technique allows for the detection of hydrogen at very low concentrations and can provide insights into how hydrogen is distributed in relation to defects or dopants.

Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM): These imaging techniques can be used to observe the surface morphology and microstructural features of TiAlN coatings before and after hydrogen exposure. Changes in surface topography can indicate hydrogen-induced damage or alterations in the material.

By combining these experimental techniques with computational simulations, researchers can gain a comprehensive understanding of hydrogen-TiAlN interactions and validate the theoretical predictions made through density functional theory calculations.

What other material properties, beyond hydrogen permeation, make TiAlN an attractive candidate for applications in the hydrogen economy and nuclear industry?

Beyond its exceptional hydrogen permeation resistance, titanium aluminium nitride (TiAlN) possesses several other material properties that make it an attractive candidate for applications in the hydrogen economy and nuclear industry:

High Hardness and Wear Resistance: TiAlN is known for its superior hardness and wear resistance, making it suitable for protective coatings in harsh environments. This property is particularly beneficial in applications where mechanical wear and abrasion are concerns, such as in hydrogen storage tanks and reactors.

Thermal Stability: TiAlN exhibits excellent thermal stability, maintaining its mechanical properties at elevated temperatures. This characteristic is crucial for applications in nuclear reactors, where materials are subjected to high temperatures and radiation.

Chemical Resistance: The chemical inertness of TiAlN against corrosive environments enhances its durability in hydrogen-rich atmospheres. This property is vital for ensuring the longevity and safety of materials used in hydrogen storage and transport systems.

Low Friction Coefficient: TiAlN coatings can provide a low friction surface, which is advantageous in reducing wear and improving the efficiency of mechanical systems. This property can enhance the performance of components in hydrogen fuel cells and other energy systems.

Versatile Fabrication Techniques: TiAlN can be deposited using various techniques, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), allowing for precise control over the coating thickness and microstructure. This versatility enables the tailoring of TiAlN coatings to meet specific application requirements.

Electrical Conductivity: While TiAlN is primarily a dielectric material, its electrical properties can be tuned through doping or structural modifications. This tunability can be beneficial in applications where electrical conductivity is required, such as in sensors or electronic devices used in hydrogen technologies.

These combined properties position TiAlN as a promising material for enhancing the safety, efficiency, and durability of systems in the hydrogen economy and nuclear industry, making it a focal point for future research and development.