Abstract
We present neutron diffraction, electronic structure calculations, and optical vibrational spectroscopic characterization of hydronium uranyl phosphate (HUP), the synthetic analog of chernikovite ((H3O)(UO2)(PO4)·3H2O) to gain insight into structural features of the hydronium cation in the solid state. HUP crystallizes in P21/c instead of previously reported P4/ncc1at room temperature and Pccn below 302 K. Lower symmetry was required due to hydronium and interstitial water positions within the structure. Crystallographic positions of hydronium cations determined from powder neutron diffraction data are bolstered by Raman and attenuated total reflectance infrared spectroscopic measurements and are further informed by density functional theory with phonon eigenvector analysis for spectral assignments. Finally, HUP and its arsenate analog (trogerite, (H3O)(UO2)(AsO4)·3H2O), (HUAs) were studied using He2+irradiation as an analog for α radiolysis to investigate the irradiation stability of these phases and the stability of hydronium cations in the solid state. Dose studies were employed wherein each sample was irradiated to 5, 10, 15, 25, and 50 MGy. Structural insight regarding irradiated materials is gained using optical vibrational spectroscopy and powder X-ray diffraction. Surprising irradiation stability of HUAs was found up to 50 MGy of dose, which may have important implications for understanding and modeling the geologic stability of legacy U.
| Original language | English |
|---|---|
| Pages (from-to) | 14138-14152 |
| Number of pages | 15 |
| Journal | Inorganic Chemistry |
| Volume | 64 |
| Issue number | 28 |
| DOIs | |
| State | Published - Jul 21 2025 |
Funding
This material is based upon work supported under an Integrated University Program Graduate Fellowship. In addition, the University of Notre Dame supported this work and a portion was funded by the U.S. Department of Energy, National Nuclear Security Administration, Office of Defense Nuclear Nonproliferation R&D. The authors thank Jay Laverne for his operation of and expertise with the 9s accelerator and He-ion irradiation experiments. We also thank Drs. Samuel Eaton, Jennifer Niedziela, Daniel Felton and Kathryn Peruski for their helpful comments and radiological control technicians Keith Gilbert and JJ Quinn at ORNL. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The beam time was allocated to POWGEN on proposal number IPTS-30421.1. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).