| Autor: |
Lender T; Institute of Crystallography, RWTH Aachen University, Aachen 52066, Germany., Murphy G; Institute of Fusion Energy and Nuclear Waste Management (IFN-2), Forschungszentrum Jülich GmbH, Jülich 52428, Germany., Bazarkina E; Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany.; The Rossendorf Beamline at ESRF, The European Synchrotron, Grenoble 38043, France., Bukaemskiy A; Institute of Fusion Energy and Nuclear Waste Management (IFN-2), Forschungszentrum Jülich GmbH, Jülich 52428, Germany., Gilson S; Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany., Henkes M; Institute of Fusion Energy and Nuclear Waste Management (IFN-2), Forschungszentrum Jülich GmbH, Jülich 52428, Germany., Hennig C; Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany.; The Rossendorf Beamline at ESRF, The European Synchrotron, Grenoble 38043, France., Kaspor A; Institute of Fusion Energy and Nuclear Waste Management (IFN-2), Forschungszentrum Jülich GmbH, Jülich 52428, Germany., Marquardt J; Institut für Geowissenschaften, Goethe-Universität Frankfurt, Frankfurt am Main 60438, Germany., Nießen J; Institute of Mineral Engineering, RWTH Aachen University, Aachen 52074, Germany., Peters L; Institute of Crystallography, RWTH Aachen University, Aachen 52066, Germany., Poonoosamy J; Institute of Fusion Energy and Nuclear Waste Management (IFN-2), Forschungszentrum Jülich GmbH, Jülich 52428, Germany., Rossberg A; Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany.; The Rossendorf Beamline at ESRF, The European Synchrotron, Grenoble 38043, France., Svitlyk V; Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany.; The Rossendorf Beamline at ESRF, The European Synchrotron, Grenoble 38043, France., Kvashnina KO; Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany.; The Rossendorf Beamline at ESRF, The European Synchrotron, Grenoble 38043, France., Huittinen N; Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany.; Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin 14195, Germany. |
| Abstrakt: |
Crystalline materials such as monazite have been considered for the storage of radionuclides due to their favorable radiation stability. Understanding their structural chemical response to radiation damage as solid solutions is a key component of determining their suitability for radionuclide immobilization. Herein, high-resolution structural studies were performed on ceramics of the monazite solid solution La 1- x Ce x PO 4 ( x = 0.25, 0.5, 0.75, 1) in order to understand the role of structural chemistry on irradiation stability. Ceramic samples were irradiated with 14 MeV Au ions with 10 14 ions/cm 2 and 10 15 ions/cm 2 to simulate the recoil of daughter nuclei from the alpha decay of actinide radionuclides. The extent of radiation damage was analyzed in detail using scanning electron microscopy (SEM), Raman spectroscopy, grazing incidence X-ray diffraction (GI-XRD), and high-energy-resolution fluorescence detection extended X-ray absorption fine structure (HERFD-EXAFS) spectroscopy. SEM and Raman spectroscopy revealed extensive structural damage as well as the importance of grain boundary regions, which appear to impede the propagation of defects. Both radiation-induced amorphization and recrystallization were studied by GI-XRD, highlighting the ability of monazite to remain crystalline at high fluences throughout the solid solution. Both, diffraction and HERFD-EXAFS experiments show that while atomic disorder is increased in irradiated samples compared to pristine ceramics, the short-range order was found to be largely preserved, facilitating recrystallization. However, the extent of recrystallization was found to be dependent on the solid solution composition. Particularly, the samples with uneven ratios of solute cations, La 0.75 Ce 0.25 PO 4 and La 0.25 Ce 0.75 PO 4 were observed to exhibit the least apparent radiation damage resistance. The findings of this work are discussed in the context of the monazite solid solution chemistry and their appropriateness for radionuclide immobilization. |
