Recent Advances in the Transuranium Compounds Studies at JRC-KA

Here we report recent studies performed at the JRC-KA (Karlsruhe, Germany) on Actinides based compounds.<br/>New devices have been commissioned to perform low temperature measurements on nuclear materials extending fundamental and applied research possibilities and giving access to their thermodynamic, magnetic, electronic, thermal transport properties and especially thermal expansion down to 1.8 K under magnetic field properties. These techniques have supported the examination of re-examination of systems produced in house (Np, Pu, Am based oxides and intermetallic).<br/>We will present results on UO₂ oxides doped by RE (= Nd, La) and Am studies using XRD, heat capacity and magnetization with consideration of the ageing effect induced by 241Am self-heating. Interestingly Americium doping is affectingt magnetic feature of UO₂ the more [1].<br/>Then, we will report on the structural, magnetic and thermodynamic studies of Pu-based perovskite PuAlO3 and PuBaO3 compounds showing intriguing magnetic features (antiferromagnetic at 15 K and ferromagnetic at 164 K ground state, respectively). Both systems present μ_eff~0.9 μ_B obtained by a Modified Curie-Weiss law above ordering state in the paramagnetic state in contrary to reported values [2].<br/>Finally, examination of Transuranium Fluoride systems by magnetisation will be reported with tentatively antiferromagnetic ordering developing below 6K.<br/>[1] J.-C. Griveau et al., J<i>. Appl. </i><i>Phys.</i> <b>13</b>2, 185103 (2022)<br/>[2] S. Skanthakumar et al., <i>Inorg. Chem.</i> 2023, 62, <b>39</b>, 15891–15901