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NAGAME Y, SATO TK. Chemical characterization of heavy actinides and light transactinides - Experimental achievements at JAEA. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2024; 100:165-189. [PMID: 38462500 PMCID: PMC11105975 DOI: 10.2183/pjab.100.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 11/17/2023] [Indexed: 03/12/2024]
Abstract
The chemical characterization of the heaviest elements at the farthest reach of the periodic table (PT) and the classification of these elements in the PT are undoubtedly crucial and challenging subjects in chemical and physical sciences. The elucidation of the influence of relativistic effects on their outermost electronic configuration is also a critical and fascinating aspect. However, the heaviest elements with atomic numbers Z ≳ 100 must be produced at accelerators using nuclear reactions of heavy ions and target materials. Therefore, production rates for these elements are low, and their half-lives are as short as a few seconds to a few minutes; they are usually available in a quantity of only a few atoms at a time. Here, we review some highlighted studies on heavy actinide and light transactinide chemical characterization performed at the Japan Atomic Energy Agency tandem accelerator facility. We discuss briefly the prospects for future studies of the heaviest elements.
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Affiliation(s)
- Yuichiro NAGAME
- Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Naka-gun, Ibaraki 319-1195, Japan
| | - Tetsuya K. SATO
- Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Naka-gun, Ibaraki 319-1195, Japan
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Schädel M, Nagame Y. From SRAFAP to ARCA and AIDA – developments and implementation of automated aqueous-phase rapid chemistry apparatuses for heavy actinides and transactinides. RADIOCHIM ACTA 2019. [DOI: 10.1515/ract-2019-3103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The development of automated rapid chemistry techniques and their application for batch-wise, chromatographic separations of heavy elements in the liquid-phase are outlined. Starting in the mid-1970s with manually performed separations using pressurized liquid-chromatography techniques, this development led to the first version of the Automated Rapid Chemistry Apparatus, ARCA, in the early 1980s. After a breakthrough to a much higher level of automation and miniaturization, the new apparatus ARCA II was built in the late 1980s. Based on it, the Automated Ion-exchange separation apparatus coupled with the Detection system for Alpha spectroscopy, AIDA, became operational in the late 1990s. In the context of technical and technological advancements, this article discusses the successful application of these instruments for (i) the search for superheavy elements, (ii) cross section measurements of actinide elements produced in multi-nucleon transfer reactions with actinide targets, (iii) chemical separation and characterization of the heavy actinides mendelevium, Md, and lawrencium, Lr, and (iv) studies of the transactinide elements rutherfordium, Rf, dubnium, Db, and seaborgium, Sg. Details of the separations are outlined together with the big advancements made over time and the limitations reached. For the transactinide elements, examples are given for their observed chemical behavior; often affected by an interplay between hydrolysis and complex formation. Influenced by relativistic effects, chemical properties of these elements sometimes deviated from those of their lighter homologs in the Periodic Table.
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Affiliation(s)
- Matthias Schädel
- GSI Helmholtzzentrum für Schwerionenforschung GmbH , 64291 Darmstadt , Germany
| | - Yuichiro Nagame
- Advanced Science Research Center, Japan Atomic Energy Agency (JAEA) , Tokai-mura, Ibaraki 319-1195 , Japan
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Abstract
Abstract
The chemistry of superheavy elements - or transactinides from their position in the Periodic Table - is summarized. After giving an overview over historical developments, nuclear aspects about synthesis of neutron-rich isotopes of these elements, produced in hot-fusion reactions, and their nuclear decay properties are briefly mentioned. Specific requirements to cope with the one-atom-at-a-time situation in automated chemical separations and recent developments in aqueous-phase and gas-phase chemistry are presented. Exciting, current developments, first applications, and future prospects of chemical separations behind physical recoil separators (“pre-separator”) are discussed in detail. The status of our current knowledge about the chemistry of rutherfordium (Rf, element 104), dubnium (Db, element 105), seaborgium (Sg, element 106), bohrium (Bh, element 107), hassium (Hs, element 108), copernicium (Cn, element 112), and element 114 is discussed from an experimental point of view. Recent results are emphasized and compared with empirical extrapolations and with fully-relativistic theoretical calculations, especially also under the aspect of the architecture of the Periodic Table.
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Affiliation(s)
- M. Schädel
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan / GSI Helmholtz Center for Heavy Ion Research, 64291 Darmstadt, Germany
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Kasamatsu Y, Kikutani Y, Kino A, Komori Y, Yokokita T, Yoshimura T, Takahashi N, Shinohara A. Solvent extraction of Zr and Hf from hydrochloric acid using tributylphosphate for the extraction of element 104, rutherfordium. RADIOCHIM ACTA 2013. [DOI: 10.1524/ract.2013.2056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
SummaryFor the solvent extraction experiment on element 104 (Rf), solvent extraction of Zr and Hf as its homologues was performed in tributylphosphate (TBP)/hydrochloric acid (HCl) system using the carrier-free radiotracers88Zr and175Hf. Time dependences of the distribution ratios of Zr and Hf were investigated using 6.1 and 10.0M HCl and 0.5 and 2.0M TBP benzene solutions. The distribution ratios in equilibrium were determined for these elements as a function of HCl concentrations in the range of 4.1-10.2M. We found that the neutral chloride complexes of Zr and Hf were formed and extracted into the organic phase within 20 min in HCl with a concentration higher than 6 M. From the results, we propose that solvent extraction of Rf from 4-8M HCl into 2.0M TBP benzene is suitable for investigating the chloride complexation properties of Rf. In addition, for the development of the rapid liquid-liquid extraction apparatus, three types of microchannel devices, namely, a micro reactor, capillary tube and micro-chemical chip, were tested as a mixing-solution part in the apparatus. The chemical reactions of Zr and Hf in the extraction were found to be fast only when using the microchemical chip, which is important for investigations with the 68-s261Rf.
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Affiliation(s)
- Y. Kasamatsu
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Y. Kikutani
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - A. Kino
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Y. Komori
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - T. Yokokita
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - T. Yoshimura
- Radioisotope Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - N. Takahashi
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - A. Shinohara
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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Haba H, Tsukada K, Asai M, Toyoshima A, Ishii Y, Toume H, Sato T, Nishinaka I, Ichikawa T, Ichikawa S, Nagame Y, Sato W, Matsuo K, Kitamoto Y, Tashiro Y, Shinohara A, Saito J, Ito M, Ikezawa T, Sakamaki M, Goto S, Kudo H, Kikunaga H, Arai M, Kamataki S, Yokoyama A, Akiyama K, Sueki K, Oura Y, Schädel M, Brüchle W, Kratz JV. Extraction behavior of rutherfordium into tributylphosphate from hydrochloric acid. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.2007.95.1.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The extraction behavior of rutherfordium (Rf) into tributylphosphate (TBP) from hydrochloric acid (HCl) has been studied together with those of the lighter group-4 elements Zr and Hf. The extractability of261Rf,169Hf, and85Zr into TBP was investigated under identical conditions in 7.2–8.0 M HCl by on-line reversed-phase extraction chromatography. The percent extractions of Rf, Hf, and Zr into the TBP resin increase steeply with increasing HCl concentration, and the order of extraction is Zr > Hf ≈ Rf. By considering the order of chloride complexation among these elements, it is suggested that the stability of the TBP complex of Rf tetrachloride is lower than those of Zr and Hf.
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Nagame Y, Tsukada K, Asai M, Toyoshima A, Akiyama K, Ishii Y, Kaneko-Sato T, Hirata M, Nishinaka I, Ichikawa S, Haba H, Enomoto S. Chemical studies on rutherfordium (Rf) at JAERI. RADIOCHIM ACTA 2007. [DOI: 10.1524/ract.2005.93.9-10.519] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
SummaryChemical studies on element 104, rutherfordium (Rf), at JAERI (Japan Atomic Energy Research Institute) are reviewed. The transactinide nuclide261Rf has been produced in the reaction248Cm(18O, 5n) at the JAERI tandem accelerator with the production cross section of about 13 nb. On-line anion-exchange experiments on Rf together with the lighter homologues, group-4 elements Zr and Hf, in acidic solutions have been conducted with a rapid ion-exchange separation apparatus. From the systematic study of the anion-exchange behavior of Rf, it has been found that the properties of Rf in HCl and HNO3solutions are quite similar to those of Zr and Hf, definitely confirming that Rf is a member of the group-4 elements. However, we have observed an unexpected chemical behavior of Rf in HF solutions; the fluoride complex formation of Rf is significantly different from those of the homologues. Prospects of extending chemical studies on transactinide elements in the near future at JAERI are briefly considered.
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Abstract
The number of chemical elements has increased considerably in the last few decades. Most excitingly, these heaviest, man-made elements at the far-end of the Periodic Table are located in the area of the long-awaited superheavy elements. While physical techniques currently play a leading role in these discoveries, the chemistry of superheavy elements is now beginning to be developed. Advanced and very sensitive techniques allow the chemical properties of these elusive elements to be probed. Often, less than ten short-lived atoms, chemically separated one-atom-at-a-time, provide crucial information on basic chemical properties. These results place the architecture of the far-end of the Periodic Table on the test bench and probe the increasingly strong relativistic effects that influence the chemical properties there. This review is focused mainly on the experimental work on superheavy element chemistry. It contains a short contribution on relativistic theory, and some important historical and nuclear aspects.
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Affiliation(s)
- Matthias Schädel
- KPII-Kernchemie, Gesellschaft für Schwerionenforschung mbH, Planckstrasse 1, 64291 Darmstadt, Germany.
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Haba H, Tsukada K, Asai M, Toyoshima A, Akiyama K, Nishinaka I, Hirata M, Yaita T, Ichikawa SI, Nagame Y, Yasuda KI, Miyamoto Y, Kaneko T, Goto SI, Ono S, Hirai T, Kudo H, Shigekawa M, Shinohara A, Oura Y, Nakahara H, Sueki K, Kikunaga H, Kinoshita N, Tsuruga N, Yokoyama A, Sakama M, Enomoto S, Schädel M, Brüchle W, Kratz JV. Fluoride Complexation of Element 104, Rutherfordium. J Am Chem Soc 2004; 126:5219-24. [PMID: 15099106 DOI: 10.1021/ja031824u] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluoride complexation of element 104, rutherfordium (Rf), produced in the 248Cm(18O,5n)261Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchange chromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the 18O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effects on the fluoride complexation of Rf.
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Affiliation(s)
- Hiromitsu Haba
- Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195, Japan.
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