Predicting Material Defects with X-Ray Imaging

Argonne researchers are the first to capture the formation of nanomaterial defects in near-real time. Their work will help other researchers model the behavior of materials, a step that is key to engineering stronger, more reliable materials. (Image courtesy of Mark Lopez/Argonne National Laboratory.)

Researchers at Argonne National Laboratory in Chicago recently discovered a new approach to analyzing and predicting the formation of defects in materials using x-ray imaging.

Using this method, they were able to capture images of the creation of structural defects in palladium, when exposed to hydrogen for the first time ever.

In a study published in the journal Nature Materials, researchers focused on forming defects at the nanoscale level using a palladium crystal infused with hydrogen at high pressure while also exposing it to powerful X-rays. The X-rays scattered and by capturing this dispersion, the researchers were able to calculate the changes in atom positions within the crystal.

Defect engineering involves changing a material’s properties by forming defects in a material, aiding in the engineering of more reliable materials for everyday items. This also increased clarity in the processes involved in changing attributes of materials.

This discovery will help engineers better understand and improve materials for a variety of uses with near-real time monitoring of the formation changes in materials at the atomic scale.

Argonne physicist Ross Harder said, “In some ways, we got the one-in-a-million shot, because defects occurring within the crystal don't always happen due to the complex nature of the process.”

To map out changes in the metal palladium on the nanoscale, researchers used the diffraction patterns of X-rays. (Image courtesy of Mark Lopez/Argonne National Laboratory.)

The changes shown in the scans at Argonne demonstrate the multitude of ways in which defects alter a material’s properties and their responses to external stimuli. In this example, the defects altered the pressures at which palladium can store and release hydrogen. This could prove useful knowledge for developing hydrogen storage, sensing and purification applications.

The process of adding impurities is known as doping. These additions create defects, changing the electrical properties of the materials for various uses in different forms of technology.

Andrew Ulvestad from Argonne said, "Defect engineering is based on the idea that you can take something you already know the properties of and, by putting in defects or imperfections, engineer things with improved properties." He added, "The practice applies not only to metals but any material that has a crystal structure, like those found in solar cells and battery cathodes."

Defect engineering is most commonly utilized in semiconductor development, including silicon from electronics in laptops and cellphones, among others.

While this study is the first of its kind, Ulvestad is hoping this will act as a “roadmap for other researchers.” Adding, “We've shown them a way to model this system and systems that have similar dynamics.”

For more material defect news, find out how to turn graphene’s defects into assets.