Washington State University researchers, led by Malin C. Dixon Wilkins, have made a major advance in understanding thorutite (ThTi₂O₆), a compound considered for nuclear waste storage. Working alongside Natalie Yaw, Xiaofeng Guo, John S. McCloy, and Neil C. Hyatt, the team synthesized a previously hard-to-make version of thorutite—the α-polymorph—using a solid-state route, marking a first in the field.
The team compared this α-polymorph with the more common β form (brannerite structure). Using neutron diffraction and Raman spectroscopy, they identified subtle differences in structure and occupancy, showing a tiny but consistent substitution of titanium into the thorium site. These detailed observations help explain why the α form forms at lower temperatures and stays stable even when other forms break down.
Importantly, they measured how much energy it takes to create each form. The α-thorutite was shown to be enthalpically stable, meaning it holds together naturally at lower temperatures. In contrast, the β form is only stable under heat. This insight is essential for long-term storage of radioactive elements like thorium, where even minor changes in stability can make or break a wasteform’s safety.
Their discovery offers a safer, scalable, and less energy-intensive method to prepare materials that could one day be used to contain dangerous nuclear waste. And with many compositions still unexplored, the future for thorutite research looks promising.
Malin Christian John Dixon Wilkins, Natalie Yaw, Xiaofeng Guo, John Stuart McCloy, Neil C. Hyatt, “Synthesis, structure, and thermodynamic analysis of the polymorphs of thorutite, ThTi2O6,” Journal of Solid State Chemistry, 350, 125476 (2025). https://doi.org/10.1016/j.jssc.2025.125476