Activation analysis of gadolinium impurity in high purity europium oxide

An analytical method for determining Gd impurity in high purity Eu2O3 is proposed, which makes use of neutron activation and cation-exchange separation to examine its suitability as target material for the production of sup(152m,152,154)Eu. Long-term irradiation of an Eu sample resulted in 153Gd activity amounting to 1.8 times that of the same nuclide produced from an equal quantity of Gd by (n, γ) reaction. This experimental value is quite consistent with that obtained by calculation under the assumption that the 153Gd results from nuclear reaction on 151Eu induced by secondary neutrons. For the accurate determination of Gd, Gd impurity was separated from the Eu sample prior to neutron irradiation in order to reduce the self-shielding effect in the Eu sample. Separation by cation-exchange with α-hydroxyisobutyrate (0.33 M, pH 3.77) made it possible to reduce the content of Eu in the Gd fraction below 7x10-3%. This sufficed to assure that the 159Gd content in sup(152m)Eu was smaller than 1x10-3%. For the determination of Gd content below 104 ppm, however, should necessitate further purification of the irradiated Gd fraction. (auth.)