NUCLEAR SIZE AND SHAPE EFFECT IN CHEMICAL ISOTOPE EFFECT OF GADOLINIUM USING DICYCLOHEXANO-18-CROWN-6 |
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| Authors: | Tadashi Yamamoto Jun Inagawa Katsubumi Gunji Kazuo Watanabe Kazushige Nishizawa |
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| Affiliation: | 1. Department of Nuclear Engineering , Osaka University, Japan , 2-1 Yamadaoka, Suita, Osaka, 565-087I, Japan;2. Analytical Chemistry Laboratory, Japan Atomic Energy Research Institute , Tokai, Ibaraki, 319-1195, Japan |
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| Abstract: | ABSTRACT Gadolinium isotopes were fractionated in a liquid-liquid extraction system using dicyclohexano-18-crown-6. The isotope enrichment factors showed breakdowns of the conventional Bigeleisen-Mayer approximation for every condition of the initial phases; the concentrations of gadolinium and hydrochloric acid and the type of organic solvents. The nuclear mass effect and the field shift effect were estimated by use of the isotope pairs 152Gd-160Gd and 154Gd-160Gd. Since both isotopes, 152Gd and 154Gd, have the unique characteristics of the nuclear charge radii, <r2>'s, the unusual isotope effects due to the field shifts took place, while the mass effects of the other isotopes canceled the field shift effects. The maximum isotope effect was observed to be ε160,152 =0·0252 ± 0·0024 whose initial aqueous phase was 0·023 M GdCl3 in 12 M HC1, and its organic phase was 0·2 M DC18C6 in chloroform: this was 0·00315 ± 0·00030 in terms of the enrichment factor for unit mass. |
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