Non- identical thermochemical behavior of 234 U-and 238 U- isotopes in metamict britholite

A radiochemical analysis of the valence state of uranium isotopes in minerals involves isolation of the U(IV) and U(VI) valence forms and determination of the radioactivity of the U and U isotopes in each fraction. If the nuclear decay of the uranium in the minerals is accompanied by a redox process...

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Bibliographic Details
Published inApplied radiation and isotopes Vol. 119; pp. 1 - 5
Main Authors Skriplev, Mikhail I, Bogdanov, Roman V, Schwink, Lawrence R
Format Journal Article
LanguageEnglish
Published England 01.01.2017
Subjects
Metamict minerals
Natural analogues
Thermochemistry
Alpha-decay
Britholite
Uranium isotopes
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Summary:A radiochemical analysis of the valence state of uranium isotopes in minerals involves isolation of the U(IV) and U(VI) valence forms and determination of the radioactivity of the U and U isotopes in each fraction. If the nuclear decay of the uranium in the minerals is accompanied by a redox process, the distribution of the U isotope in the U(IV) and U(VI) forms will differ from that of the U isotope: oxidation leads to enrichment of the U(VI) fraction with the radiogenic U isotope; reduction facilitates enrichment of the U(IV) fraction with U. If the mineral is heated to 600-700°C before the radiochemical analysis, then an equilibrium activity ratio (AR) for both valences. The question arises: What are the processes that bring this about? The authors of this research studied changes of the AR in the U(IV) and U(VI) fractions after isochronous thermal annealing.
ISSN:0969-8043
1872-9800
DOI:10.1016/j.apradiso.2016.08.023