Researchers at Empa have recently achieved an important breakthrough in the understanding of amorphous alumina. This unusual material is defined by a simple crystalline structure and chemical formula – Al2O3. This innovative research combines machine learning, high-performance simulations, and experimental data to model the atomic structure of amorphous alumina. It uncovers some really cool future-desirable use cases across all industries, most interestingly in hydrogen.
Amorphous alumina is the most common material in the Earth’s crust. You can even find it in corundum, a mineral widely known for its beautiful color variations, such as sapphires and rubies. Amorphous alumina is particularly unique since it is absent the ordered arrangements found in crystalline materials. Instead, this creates a chaotic structure of aluminum and oxygen atoms. For further clarity on the topic, the researchers have pointed out that the hydrogen content in amorphous alumina is dependent on the manufacturing process employed.
Breakthrough Simulations
The Empa team, headed by project leader Simon Gramatte and PhD student Vladyslav Turlo, already accomplished a remarkable feat. In contribution 3, they have accurately simulated amorphous aluminum oxide with hydrogen inclusions at an atomic level. Using traditional methods, it would take longer than the age of the universe to simulate such materials. Using machine learning, the entire team can run these simulations in less than a day.
“We have shown that it is possible to accurately simulate amorphous materials,” – Vladyslav Turlo
Empa’s interdisciplinary development of this innovation through collaboration between different laboratories was crucial. To go a step further, they created a new machine learning model that integrates multiple data sources. This model can shed light on the atomic structure of amorphous Al2O3 layers. That kind of in-depth comprehension paves the way to amending the material’s aggregate to produce highly specific desirable properties.
Applications in Hydrogen Technology
Amorphous alumina, specifically, has emerged as perhaps the best use of these materials for the development of hydrogen membranes. Vladyslav Turlo is keen to explain this potential, pointing out that the material can be a huge help in producing green hydrogen, an emerging clean energy source. The introduction of hydrogen atoms into amorphous alumina leads to a dramatic improvement in its chemical behavior and indeed promotes its wide application into advanced technologies.
“Amorphous alumina is one of the most promising materials for such hydrogen membranes,” – Vladyslav Turlo
Science has demonstrated that when hydrogen content exceeds a certain threshold, these atoms start to react with oxygen in the material’s microstructure. This binding changes the oxidation states of other elements involved. Claudia Cancellieri adds, “We were able to show that, above a certain content, hydrogen binds to the oxygen atoms in the material, affecting the chemical states of the other elements.”
Ivo Utke goes into more detail with the benefits of knowing these materials down to the atomic level. “An understanding of our materials at the atomic level allows us to optimize the material’s properties, be it related to mechanics, optics, or permeability, in a much more targeted manner,” he states.
Implications for Future Research
The impact of this research reaches well beyond hydrogen technology. Simulating disordered alumina atomically with high accuracy creates exciting possibilities. This breakthrough could shake up industries from electronics to the chemical industry. By controlling the properties of amorphous alumina, manufacturers of many industries would be able to achieve better product performance and processing efficiency.
According to Turlo, this knowledge further helps understand how the hydrogen content drives the gas diffusion process through the material. “Thanks to our model, we can gain a much better understanding of how the hydrogen content in the material favors the diffusion of gaseous hydrogen with respect to other larger molecules,” he explains.
“Clarity out of chaos: In amorphous alumina, aluminum atoms (gray) and oxygen atoms (red) do not arrange in an ordered crystalline structure. The model also visualizes hydrogen atoms (blue) closely binding to neighboring oxygen atoms, which alters the material’s properties.” – Empa
This collaborative, seed-stage research demonstrates the transformative capabilities of amorphous alumina to ignite innovative new applications. Beyond these contributions, it sets the stage for other studies to follow. Pairing machine learning with hypothesis-driven research might unlock new machines, materials, medicines and more.