Dependence of Uranium Oxide Polymorphism on Plasma Synthesis Conditions

Journal Article · 13 March 2024 · Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

DOI: https://doi.org/10.1021/acs.jpca.3c08442 · OSTI ID:2341967

Weerakkody, Emily N.  ^[1]; Koroglu, Batikan  ^[1]; Dai, Zurong ^[1]; Rodriguez, Kate E.  ^[1]; Balboni, Enrica  ^[1]

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1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Here, we synthesized uranium oxide nanoparticles using a plasma flow reactor (PFR) and studied the effects of three different experimental parameters on the resulting morphologies and speciation of the particles: (1) collection duration, (2) collection substrate temperature, and (3) radial collection position due to radial temperature gradients in the PFR. We also induced three distinct temperature histories along the axis of the plasma flow reactor by varying the gas flow rates downstream of the plasma torch. Transmission electron microscopy (TEM) analyses of collected particles showed two phases of uranium oxides (fcc-UO₂ and α-UO₃). The chemical compositions of the resulting uranium oxide particles were not altered by the three parameters investigated in this work but varied based on the temperature history induced. Preheating of the collection substrate led to deposition of fewer particles, which is attributed to a reduction in thermophoretic force caused by the reduced temperature gradient for preheated substrates. The relative amounts of UO₂ to UO₃ and particle size varied depending on the cooling history employed during synthesis.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 2341967
• Report Number(s): LLNL-JRNL-858110; {1082364,"Journal ID: ISSN 1089-5639"}
• Journal Information: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Journal Name: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory Journal Issue: 12 Vol. 128; ISSN 1089-5639
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English