Shedding Light on the Enigmatic TcO2 ⋅ xH2O Structure with Density Functional Theory and EXAFS Spectroscopy**

Oliveira AF, Kuc A, Heine T, Abram U, Scheinost AC (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Chemistry - A European Journal Wiley

Book Volume: 28

Article Number: e202202235

Journal Issue: 59

DOI: 10.1002/chem.202202235

Abstract

The β-emitting 99Tc isotope is a high-yield fission product in 235U and 239Pu nuclear reactors, raising special concern in nuclear waste management due to its long half-life and the high mobility of pertechnetate (TcO4−). Under the conditions of deep nuclear waste repositories, Tc is retained through biotic and abiotic reduction of TcO4− to compounds like amorphous TcO2 ⋅ xH2O precipitates. It is generally accepted that these precipitates have linear (Tc(μ-O)2(H2O)2)n chains, with trans H2O. Although corresponding Tc−Tc and Tc−O distances have been obtained from extended X-ray absorption fine structure (EXAFS) spectroscopy, this structure is largely based on analogy with other compounds. Here, we combine density-functional theory with EXAFS measurements of fresh and aged samples to show that, instead, TcO2 ⋅ xH2O forms zigzag chains that undergo a slow aging process whereby they combine to form longer chains and, later, a tridimensional structure that might lead to a new TcO2 polymorph.

Involved external institutions

Helmholtz-Zentrum Dresden-Rossendorf (HZDR) DE Germany (DE) Freie Universität Berlin DE Germany (DE)

How to cite

APA:

Oliveira, A.F., Kuc, A., Heine, T., Abram, U., & Scheinost, A.C. (2022). Shedding Light on the Enigmatic TcO2 ⋅ xH2O Structure with Density Functional Theory and EXAFS Spectroscopy**. Chemistry - A European Journal, 28(59). https://doi.org/10.1002/chem.202202235

MLA:

Oliveira, Augusto F., et al. "Shedding Light on the Enigmatic TcO2 ⋅ xH2O Structure with Density Functional Theory and EXAFS Spectroscopy**." Chemistry - A European Journal 28.59 (2022).

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