Radiochemical studies of the heaviest elements at JAEA

Nagame, Yuichiro ; Toyoshima, Atsushi; Tsukada, Kazuaki  ; Asai, Masato  ; Sato, Tetsuya   ; Schdel, M.

Chemical studies of the heaviest elements in liquid phases at JAEA (Japan Atomic Energy Agency) are reviewed. From the systematic investigation of ion-exchange chromatographic behavior of element 104, rutherfordium (Rf), based on an atom-at-a-time scale, it has been found that the properties of Rf are quite similar to those of the group-4 homologs, Zr and Hf, in the formation of chloride, nitrate, and sulfate complexes, although there are some differences in complexation strength between Rf and the lighter homologues. On the contrary, fluoride complex formation of Rf is significantly different from that of the homologues. Anionic fluoride complexation of element 105, dubnium (Db), has also been studied. The result clearly demonstrates that the fluoride complex formation of Db is considerably different from that of the group-5 homologue Ta, while the behavior of Db is similar to that of the lighter homologue Nb. A new electrochemical approach to the heaviest elements has been successfully conducted by a flow electrolytic column chromatographic method; the oxidation state of element 102, nobelium (No), with single atoms can be controlled with the developed apparatus. Prospects for the future studies on chemical properties of the heaviest elements at JAEA will be briefly considered.