Resumo

BURCIAGA-VALENCIA, D.C. et al. Synchrotron radiation study of the uranium chemical species electrodeposited for alpha spectrometry sources. Rev. mex. fis. [online]. 2011, vol.57, suppl.1, pp.21-29. ISSN 0035-001X.

Alpha spectrometry (AS) with semiconductor detectors has applications in nuclear decay data measurements, environmental, geological and nuclear wastes studies and other works requiring determination of actinide and other alpha emitter contents. In order to obtain accurate measurements by producing good resolution alpha spectra, AS sources must be thin and uniform. AS sources produced by electrodeposition consist of a radioactive deposit onto a metallic substrate (cathode of the electrolytic cell). Natural U sources prepared by the Hallstadius method have co-deposited Pt, originated from the dissolution of the anode during the electrodeposition. A recent work published else-where has reported a study on the morphology and spatial distribution of the U/Pt deposits with the related chemical speciation of U, using scanning electron microscopy with energy dispersive X-Ray spectroscopy, X-Ray photoelectron spectroscopy and X-Ray absorption fine structure (XAFS). The purpose of this work is to explain the structure of the Pt/U deposits. We have obtained new spectra of the U LIII edge XAFS by total electron yield at Stanford Synchrotron Radiation Lightsource (SSRL), BL 2-3. Grazing incidence X-Ray diffraction (GI-XRD) patterns were obtained at SSRL, BL 11-3. GI-XRD patterns show a bimodal distribution of grain sizes of Pt, with dimensions ~ 5 and 20 nm; schoepite diffraction signals suggest grain dimensions of ~5 nm, i.e. with low crystallization. XAFS spectra were fitted assuming two different structures: uranyl hydroxide and schoepite, and results were compared. U-U path shows low intensity that also may be a result of low crystallization.

Palavras-chave : Uranium; gracing incidence X-Ray diffraction; X-Ray absorption fine structure; synchrotron radiation.

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