Understanding how crystals develop within liquid metals has been difficult for researchers, largely because these materials are opaque and cannot be observed using conventional microscopy. A recent study led by the University of Sydney has demonstrated a method to directly visualise the growth of metallic crystals inside liquid metal droplets using high-resolution X-ray computed tomography. The work provides a clearer picture of how these structures form and may support new approaches in catalyst development, hydrogen production, and quantum materials.
Professor Kourosh Kalantar-Zadeh, who led the project, explained that observing this process directly has historically been challenging because gallium is so dense and non-transparent that standard imaging tools cannot penetrate it. To overcome this, the research team used X-ray computed tomography—technology more commonly associated with medical imaging—to capture 3D internal footage of metallic crystals forming and changing inside liquid gallium. The method allowed them to track rod-like and frost-pattern structures emerging over minutes and hours, offering a level of visibility not previously achievable.
Widjajana, M. S., Foley, M., Zheng, J., Allioux, F.-M., Idrus-Saidi, S. A., Kilani, M., Ruffman, C., Gaston, N., Pei, Z., Koshy, P., Spencer, M. J. S., Chiu, S.-H., Nor-Azman, N.-A., Kaner, R. B., Daeneke, T., Tang, J., Kang, M., & Kalantar-Zadeh, K. (2025). Observing growth of metallic crystals inside liquid metal solvents. Nature Communications, 16(1), 10044. https://doi.org/10.1038/s41467-025-66249-y
The study, focuses on platinum crystals forming within gallium-based liquid metals. Liquid gallium is unusual: although it appears metallic and dense, it becomes fluid at slightly above room temperature. In this state, its metallic bonding allows it to dissolve a wide range of other elements. When the concentration of a dissolved metal exceeds the solubility limit, solid crystals begin to form, much like how sugar crystallises in an oversaturated solution.
Professor Kourosh Kalantar-Zadeh from the University of Sydney stated,
“This study illustrated how X-ray computed tomography can overcome the challenge of observing crystal growth within liquid metal an opaque material that is usually impossible to penetrate with light and electrons.”
Other research groups studying metal crystallisation have used indirect methods such as electron microscopy on frozen samples or surface-level spectroscopy, but these approaches can only capture static images or limited surface detail. The University of Sydney team’s use of tomography provides continuous, three-dimensional insight into the interior of a liquid metal droplet, revealing details of nucleation, orientation changes, and the progression of growth.
To initiate crystallisation for the experiment, the researchers dissolved small platinum beads into gallium and a gallium–indium alloy at around 500 °C. As the alloy cooled, platinum crystals started to emerge, forming slender rods that extended through the liquid metal. The tomography data was reconstructed into full 3D models, which made it possible to examine how the crystals evolved under different cooling conditions. Study co-author and PhD researcher Moonika Widjajana noted that imaging liquid metals in this way has long been considered nearly impossible due to their opacity and density, and the approach provides a workable route to study such systems without solidifying them artificially.
The ability to observe these processes in real time could inform the design of liquid-metal-grown electrodes and catalysts. Previous studies on liquid-metal systems have shown promise for producing materials useful in hydrogen evolution reactions, CO₂ conversion and other electrochemical processes. Because liquid metals can dissolve a broad range of elements, researchers are exploring whether this environment can yield new catalytic structures not possible through more traditional solid-state synthesis. Direct observation of crystal formation gives researchers the data needed to refine these material-growth pathways.
Although the current X-ray system captures growth at relatively low spatial resolution, advances in tomography—particularly those using synchrotron sources—may soon allow finer structural features to be resolved. This may make it possible to monitor defect formation, branching behaviour and subtle surface interactions that influence a crystal’s final properties.
Taken together, the new imaging method provides structural information that complements ongoing theoretical and experimental work on liquid-metal chemistry. As research groups continue exploring liquid metals in processes ranging from microelectronics to clean-energy catalysis, the ability to map how crystals emerge within these unusual solvents offers a practical advantage for designing more effective materials.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
