TERRAPUB Geochemical Journal

Geochemical Journal, Vol. 53, 2019

Application of MV-edge XANES to determination of U oxidation state in zircon

Kazuya Tanaka1* and Yoshio Takahashi2

1Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
2Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan

(Received March 30, 2019; Accepted July 3, 2019)

Abstract: We examined three natural zircon samples with different amounts of radiation doses (1.9 × 1015 - 6.8 × 1015 α-decay events/mg) using MV-edge and LIII-edge U X-ray absorption near-edge structure (XANES). Analysis of XANES spectra at both MV-edge and LIII-edge suggested that the oxidation state of U in the zircon sample with the highest radiation dose is tetravalent. The XANES spectra of the two other samples with lower radiation doses suggested a mixture of U(IV) and U(VI), while the possibility of U(V) was not excluded. This is the first work on the application of MV-edge U XANES to the oxidation state of U in natural zircon.
Key words: oxidation state, U, MV-edge XANES, zircon

*Corresponding author E-mail: tanaka.kazuya@jaea.go.jp