Chemical and nuclear properties of Rutherfordium (Element 104)

Abstract

The chemical-properties of rutherfordium (Rf) and its group 4 homologs were studied by sorption on glass support surfaces coated with cobalt(II)ferrocyanide and by solvent extraction with tributylphosphate (TBP) and triisooctylamine (TIOA). The surface studies showed that the hydrolysis trend in the group 4 elements and the pseudogroup 4 element, lb, decreases in the order Rf>Zr≈Hf>Th. This trend was attributed to relativistic effects which predicted that Rf would be more prone to having a coordination number of 6 than 8 in most aqueous solutions due to a destabilization of the 6d5/2 shell and a stabilization of the 7pI/2 shell. This hydrolysis trend was confirmed in the TBP/HBr solvent extraction studies which showed that the extraction trend decreased in the order Zr>Hf>Rf?Ti for HBr, showing that Rf and Ti did not extract as well because they hydrolyzed more easily than Zr and Hf. The TIOA/HF solvent extraction studies showed that the extraction trend for the group 4 elements decreased in the order Ti>Zr≈Hf>Rf, in inverse order from the trend of ionic radii Rf>Zr≈Hf>Ti. An attempt was made to produce 263Rf (a) via the 248Cm(22Ne, α3n) reaction employing thenoyltrifluoroacetone (TTA) solvent extraction chemistry and (b) via the 249Bk(18O,4n) reaction employing the Automated Rapid Chemistry Apparatus (ARCA). In the TTA studies, 16 fissions were observed but were all attributed to 256Fm. No alpha events were observed in the Rf chemical fraction. A 0.2 nb upper limit production cross section for the 248Cm(22Ne, α3n)263Rf reaction was calculated assuming the 500-sec half-life reported previously by Czerwinski et al. [CZE92A].