Promethium: To Strive, to Seek, to Find and Not to Yield

Abstract

Promethium (Pm), element #61, got its name from the Greek Titan Prometheus, who stole fire from Zeus and passed it to people. The only element in the lanthanide series of the periodic table with no stable isotopes, Pm has found an impressive number of applications since its announcement in 1947 after World War II. Despite promethium having 38 known isotopes, 147 Pm is by far the most utilized and useful one. Promethium is used in long-life atomic batteries for satellites or space probes, satellite-to-submarine laser communication systems, "cosmic clocks" for the measurement of cosmic rays lifetime, monitoring of the changes in water content of citrus leaves caused by wetting and drying cycles in the soil, radiotherapy, and even for prevention of dandruff, to name but a few applications. During the Moon expeditions, Pm was used to illuminate instruments in the Apollo landing modules; currently it is used during preparations for long-term interplanetary missions (e.g., Mars) to simulate space conditions on Earth. This mini review offers a comprehensive illustration of promethium's history, synthesis techniques, properties, and its major applications in science, technology, and everyday life.

Leaching recovery of rare earth elements from the calcination product of a coal coarse refuse using organic acids

“…REEs are generally classified into two sub-groups according to their atomic weights and locations in the periodical table 2,3 , namely light rare earth elements (LREEs) and heavy rare earth elements (HREEs). Promethium (Pm) is produced by radioactive decay and considered as the only element listed in the periodical table without stable isotopes 4,5 . The global production of REEs was 210000 metric tons of REO in 2019 6 .…”

Divalent and trivalent neodymium photoluminescence in NaMgF3:Nd

“…In order to justify the attribution of the additional PL emissions and excitations to Nd 2+ centres, a comparison of the transition energies was attempted regarding the isoelectronic Pm 3+ ion. Pm 3+ is an incredibly challenging ion to study in any detail as all isotopes are highly radioactive [24]. However, Carnall provided a list of transitions and their corresponding energies for the LaF 3 :Pm compound [41], and the subsequent analysis and attributions are primarily based on that list, alongside data obtained for the LaCl 3 compound [26].…”

“…The host-referred binding energy (HRBE) diagram for the various NaMgF 3 :Ln systems suggests that a range of additional Ln 2+ ions, including Pr 2+ , Nd 2+ , Ho 2+ , Er 2+ , and Tm 2+ will be stable in the host after X-ray exposure [19]. Of particular interest is the Nd 2+ ion, due in part to its rich 4f 4 electronic structure that allows optical transitions ranging from the visible to the infrared that could be used for infrared lasing [24,25]. Additionally, Nd 2+ is isoelectronic to the highly unstable and seldom studied Pm 3+ ion [24][25][26], and a relative lack of spectral information is currently available for both Pm 3+ and Nd 2+ ions, encouraging attempts to better characterise the luminescence properties of Nd 2+ .…”

Observation of a promethium complex in solution

“…Nowadays, mostly synthetic radioisotope 147 Pm (with half-life τ 1/2 = 2.62 years) is produced and isolated in small quantities through nuclear fission in reactors and subsequent tedious purification steps for many applications. Promethium uses range from long-life nuclear batteries used in space craft to radiation therapy 7 , 8 . A key obstacle impeding the efficient recovery of this critical element resides in our limited comprehension of the Pm coordination chemistry.…”