Nearly 80 years after scientists at Oak Ridge National Laboratory discovered an extremely rare radioactive element called promethium, a team at the lab published a groundbreaking study on the subject that could “rewrite chemistry books,” according to ORNL.
Research published in Nature on May 22 marks the first time scientists have discovered the element’s key characteristics, although the study could have implications far beyond promethium (No. 61 on the periodic table).
One of the most critical discoveries from the research is the bond length between promethium and surrounding atoms, a previously unknown measurement that unlocks some of the element’s properties.
Only about one pound of promethium exists on Earth at any time. Promethium is mainly used for research, but also in nuclear batteries used for pacemakers and space exploration.
The new research could help scientists expand these applications and possibly discover new ones for an element that remains relatively unexplored.
ORNL is the only producer of promethium-147 in the US. The unique capabilities come from the High Flux Isotope Reactor, one of the world’s most powerful research nuclear reactors. The reactor bombards materials with a concentrated beam of neutrons to create unique materials.
Among these materials is plutonium-238, produced for generators during NASA space missions. There is also californium-252, used to start up nuclear reactors.
The High Flux Isotope Reactor, which has been operational for nearly 60 years, is one of the few facilities in the world that can create man-made elements heavier than uranium.
Promethium was kept secret from ORNL until after the Manhattan Project
Promethium was first produced as a byproduct of uranium fission in the laboratory’s graphite reactor in 1945 by Charles Coryell, Jacob A. Marinsky, and Lawrence E. Glendenin.
The scientists named the new element after Prometheus, a Titan and god of fire in Greek mythology, who disobeyed the gods of Olympus by bringing fire to humans. The scientists kept the discovery of promethium a secret until years after World War II ended and Oak Ridge’s scientific mission expanded beyond the Manhattan Project.
Their discovery of promethium filled a gap in the periodic table. Every other element in the group known as lanthanides had already been discovered and studied.
Lanthanides are the 15 elements from lanthanum No. 57 to lutetium No. 71. They are rare earth elements that are essential to modern technologies such as smartphones, laptops, car batteries, lasers and some cancer treatments.
ORNL research increases efficiency with difficult-to-study promethium
For years, studies of lanthanides have not included promethium, partly due to its rarity and instability.
The isotope produced by ORNL researchers, promethium-147, has a half-life of only 2.6 years. That means that by the time scientists have actually produced the radioactive material, it has already started to decay into another element.
“Preparing to make a reasonable amount of promethium, especially in a chemically pure form, is quite an undertaking,” Ilja Popovs, a staff scientist who co-led the study, told Knox News. “Producing and handling sufficient quantities of any isotope of promethium is quite a challenge and requires special facilities and certainly expertise.”
It took scientists using multiple leading facilities four months to isolate and purify the sample of promethium.
Popovs, together with Alex Ivanov and Santa Jansone-Popova, led a team of 18 authors on the study. The group used ORNL’s high flux isotope reactor and hot cells to protect them from radiation. The laboratory’s Summit supercomputer, one of the ten fastest computers in the world, was also used in the study.
New promethium discoveries end up in technology
The scientists made new discoveries about the contraction of lanthanides, a phenomenon in which the atoms of the elements become smaller as their atomic number increases, changing their properties.
The team found that shrinkage slows significantly in the lanthanide series after promethium.
This new discovery could increase efficiency in separating lanthanides, a crucial process for using the elements in modern devices.
“Finding new and better ways that allow more efficient separation of lanthanides is extremely important, and there are quite a few scientists and research groups working in that field,” Popovs said. “We hope that we will add an additional piece of information that will help us design better processes.”
ORNL has a legacy of element discovery
ORNL is credited with the discovery of three elements: promethium in 1945, moscovium in 2003, and tennessine in 2010. Moscovium and tennessine, developed in collaboration with a Russian laboratory, were verified as new elements by the International Union of Pure and Applied Chemistry in 2015 . .
Overall, the laboratory played a crucial role in the discovery of nine elements. The other six are rutherfordium, dubnium, seaborgium, flerovium, levermorium and oganesson, the last chemical in the current periodic table.
For Ivanov, one of the scientists who led the research, continuing the laboratory’s long legacy as a leader in scientific innovation is one of the most rewarding parts of the research. ORNL, operated by UT-Battelle, is the Department of Energy’s largest science and technology laboratory.
Daniel Dassow is a growth and development reporter focused on technology and energy. Phone 423-637-0878. Email daniel.dassow@knoxnews.com.
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