Contact
Prof. Dr. Nina Maria Huittinen
Head Solid State Chemistry of Radionuclides
n.huittinen
hzdr.de
Phone: +49 351 260 2148
Solid State Chemistry of Radionuclides Department
Research
As the name implies, the Solid State Chemistry of Radionuclides department focuses on research related to the structure and properties of solid phases containing radioactive elements. We are especially interested in crystalline inorganic solid phases such as zircon (ZrSiO4), zirconia (ZrO2), and pyrochlore (Ln2Zr2O7), as well as lanthanide (Ln-)orthophosphates of the monazite type (LnPO4). These solid phases are of relevance in the corrosion of the Zircaloy cladding surrounding spent nuclear fuels rods, or they are envisioned as ceramic hosts for the immobilization and safe disposal of specific actinide-bearing waste streams generated in the late stages of the nuclear fuel cycle. We produce polycrystalline powders or single crystals doped with actinide elements using hydrothermal, flux growth, and solid-state synthesis routes. Combining X-ray diffraction and various microscopic and spectroscopic techniques, we explore the microstructure, redox chemistry, and local structural order/disorder phenomena in the doped solid phases. With this, we aim to develop a detailed understanding of actinide immobilization in crystalline matrices on an atomic basis and to make reliable statements with regard to the performance of the host materials under repository conditions.
Latest Publication
Structural and Chemical Insights on the Incorporation of Americium into Monoclinic Zirconia (m-ZrO₂)
Murphy, G. L.; Gilson, S.; Popa, K.; Prieur, D.; Schenk, S. M.; Valu, S.-O.; Ramanantoanina, H.; Prüßmann, T.; Vitova, T.; Dardenne, K.; Rothe, J.; Colle, J.-Y.; Walter, O.; Huittinen, N. M.
Abstract
The structural-chemistry of monoclinic zirconia (m-ZrO2) has long attracted fundamental interest, whilst crucially it serves as a key barrier to radionuclide release at the fuel–zircaloy cladding interface in spent nuclear fuel. However, the incorporation of transuranic elements like americium with m-ZrO₂ remains poorly understood. Using a combination of diffraction, microscopy and spectroscopic techniques we have examined the doping of 5 mol % Am in m-ZrO2. We find that Am enters m-ZrO2 in its tetravalent oxidation state where its solubility is less than 1.05 mol %, Am4+0.0105Zr0.9895O2, attributed to the large sized Am4+ cation coupled with its preference under the synthesis conditions to adopt its trivalent form, where excess Am adopts an Am rich cubic structure consistent with C-type (Am4+/3+1-xZrx)2O3+x in space group Ia-3. Despite the limited solubility of Am4+ within m-ZrO2, the reversible high temperature phase transformation to tetragonal-ZrO2 (t-ZrO2) can be reduced from 1150 oC to 1050 oC via Am4+ incorporation. The investigation provides key insight into chemical behavior of Am and its interactions with m-ZrO₂.
Involved research facilities
- Rossendorf Beamline at ESRF DOI: 10.1107/S1600577520014265
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 41497) publication
-
Communications Chemistry 9(2025), 50
DOI: 10.1038/s42004-025-01857-9
Permalink: https://www.hzdr.de/publications/Publ-41497
Latest publication
Structural and Chemical Insights on the Incorporation of Americium into Monoclinic Zirconia (m-ZrO₂)
Murphy, G. L.; Gilson, S.; Popa, K.; Prieur, D.; Schenk, S. M.; Valu, S.-O.; Ramanantoanina, H.; Prüßmann, T.; Vitova, T.; Dardenne, K.; Rothe, J.; Colle, J.-Y.; Walter, O.; Huittinen, N. M.
Abstract
The structural-chemistry of monoclinic zirconia (m-ZrO2) has long attracted fundamental interest, whilst crucially it serves as a key barrier to radionuclide release at the fuel–zircaloy cladding interface in spent nuclear fuel. However, the incorporation of transuranic elements like americium with m-ZrO₂ remains poorly understood. Using a combination of diffraction, microscopy and spectroscopic techniques we have examined the doping of 5 mol % Am in m-ZrO2. We find that Am enters m-ZrO2 in its tetravalent oxidation state where its solubility is less than 1.05 mol %, Am4+0.0105Zr0.9895O2, attributed to the large sized Am4+ cation coupled with its preference under the synthesis conditions to adopt its trivalent form, where excess Am adopts an Am rich cubic structure consistent with C-type (Am4+/3+1-xZrx)2O3+x in space group Ia-3. Despite the limited solubility of Am4+ within m-ZrO2, the reversible high temperature phase transformation to tetragonal-ZrO2 (t-ZrO2) can be reduced from 1150 oC to 1050 oC via Am4+ incorporation. The investigation provides key insight into chemical behavior of Am and its interactions with m-ZrO₂.
Involved research facilities
- Rossendorf Beamline at ESRF DOI: 10.1107/S1600577520014265
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 41497) publication
-
Communications Chemistry 9(2025), 50
DOI: 10.1038/s42004-025-01857-9
Permalink: https://www.hzdr.de/publications/Publ-41497
