Brian Westenhaus
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By Brian Westenhaus – Dec 27, 2023, 2:00 PM CST
- The improved technique overcomes the challenge of detecting atomic state hydrogen, the smallest atom, through conventional means.
- This method allows real-time observation of hydrogen flow in metals with microscale spatial resolution, providing unprecedented detail.
- The findings, which reveal how hydrogen diffuses through grain boundaries in metals like nickel, could significantly impact the development of materials for hydrogen energy applications.
Using conventional X-rays and lasers to detect atomic state of hydrogen is particularly difficult due to its small size. A Tohoku University group of researchers may have overcome this barrier by unveiling a new visualization technique that employs an optical microscope and polyaniline to paint a better picture of how hydrogen behaves in metals.
The group has created a simple and inexpensive means to visualize the atomic state of hydrogen.
Details of their breakthrough have been published in the journal Acta Materialia.
Hydrogen or dihydrogen, is carbon dioxide free, and it has long been touted by some as a fuel source for clean energy. Yet, shifting society towards a hydrogen energy-based one requires overcoming some significant technical issues.
An essential is structural and functional materials that produce, store, transport and preserve hydrogen. To develop advanced materials for hydrogen-related applications, a fundamental understanding of how hydrogen behaves in alloys is crucial.
However, current technology falls short in this area. Detecting atomic state hydrogen – the smallest atom in the universe – with X-rays or lasers is challenging due to its unique characteristics.
Researchers are currently focusing on better analytical and visualization techniques that can incorporate high spatial and time resolutions simultaneously.
Hiroshi Kakinuma, an assistant professor at Tohoku University, and his co-authors developed a new visualization technique harnessing an optical microscope and polyaniline layer.
Kakinuma noted, “When the color of the polyaniline layer reacts with the atomic state hydrogen in metals, it changes colors, allowing us to analyze the flow of hydrogen atoms based on the color distribution of the polyaniline layer. Additionally, optical microscopes can observe the sub-millimeter-scale view with microscale spatial resolution in real time, thereby capturing hydrogen behavior with unprecedented high spatial and time resolutions.”
Thanks to this method, the researchers successfully filmed the flow of hydrogen atoms in pure nickel (Ni). The color of polyaniline changed from purple to white when reacting with hydrogen atoms in a metal.
The in situ visualization revealed that hydrogen atoms in pure Ni preferentially diffused through grain boundaries in disordered Ni atoms. Furthermore, the group found that hydrogen diffusion was dependent on the geometrical structure of the grain boundaries: the hydrogen flux grew at grain boundaries with large geometric spaces.
