Highlights

• Researchers first successfully characterized a promethium-147 coordination complex in water using X-ray absorption spectroscopy.
• Discovery reveals unique bonding characteristics of promethium that could improve lanthanide separation techniques.
• Promethium-147 is strategically important for nuclear batteries, defense systems, and potential medical applications like cancer imaging.

In a major advance for rare earth science, researchers at Oak Ridge National Laboratory have successfully characterized a promethium coordination complex in solution for the first time, offering new insights into one of the rarest and most chemically elusive lanthanides. Because promethium has no stable isotopes, it decays constantly, making it extremely difficult to isolate and study. Scientists overcame this challenge by synthesizing a stable complex of promethium-147 in water using an organic ligand and then probing its structure using X-ray absorption spectroscopy.

The news was reported (opens in a new tab) by the Department of Energy.

Apromethium coordination complex is a chemical structure in which the rare earth element promethium (Pm) is bonded to other atoms or molecules—usually called ligands—through coordinate covalent bonds.

The study revealed subtle but crucial differences in how promethium bonds compared to other lanthanides, specifically that the contraction of ionic radii slows beyond promethium (element 61). This alters bond lengths and chemical behavior, a discovery that could improve the notoriously difficult process of lanthanide separation.

These findings not only deepen our understanding of promethium’s chemistry but could also lead to more efficient methods for producing and purifying larger quantities of the element for critical technologies.

Promethium-147 is increasingly strategic due to its use in nuclear batteries, luminous paint, defense systems, and potential medical applications, such as cancer therapy and imaging. The U.S. Department of Energy (opens in a new tab) remains the world’s sole producer of this isotope. The research was supported by the DOE Office of Science and the Isotope Program (opens in a new tab), and the results were published in Nature (Driscoll et al., 2024).

Rare Earth Exchanges Reality Check

The article is factual and based on peer-reviewed research. There is no evident misinformation. While the potential applications in medicine and imaging are forward-looking, they are grounded in current research trajectories and are not speculative beyond reason. The claim that this work could lead to better separation techniques is plausible but will require further development more than likely.