This paper focuses on major phosphate-based ceramic materials relevant for the immobilisation of Pu, minor actinides, fission and activation products. Key points addressed include the recent progress regarding synthesis methods, the formation of solid solutions by structural incorporation of actinides or their non-radioactive surrogates and waste form fabrication by advanced sintering techniques. Particular attention is paid to the properties that govern the long-term stability of the waste forms under conditions relevant to geological disposal. The paper highlights the benefits gained from synergies of state-of-the-art experimental approaches and advanced atomistic modeling tools for addressing properties and stability of f-element-bearing phosphate materials. In conclusion, this article provides a perspective on the recent advancements in the understanding of phosphate based ceramics and their properties with respect to their application as nuclear waste forms.

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Bimetallic Au-Ni supported on TiO 2 were prepared using co-depositionprecipitation with urea and tested on the selective hydrogenation of 1,3butadiene. The catalyst containing the lower amount of Ni (atomic Au:Ni 1:0.08) showed a satisfying compromise between activity provided by Ni and selectivity to butenes provided by Au for this selective hydrogenation reaction. Even though Au and Ni exhibit limited miscibility in the bulk, characterizations by TPR and UV-vis spectroscopy showed evidence of interaction between Au and Ni in nanoparticles. STEM-XEDS study confirmed the formation of bimetallic nanoparticles.

This study investigates the incorporation of the minor actinide curium (Cm) in a series of synthetic LaGd PO ( x = 0, 0.24, 0.54, 0.83, 1) monazite and rhabdophane solid-solutions. To obtain information on the incorporation process on the molecular scale and to understand the distribution of the dopant in the synthetic phosphate phases, combined time-resolved laser fluorescence spectroscopy and X-ray absorption fine structure spectroscopy investigations were conducted and complemented with ab initio atomistic simulations. We found that Cm is incorporated in the monazite endmembers (LaPO and GdPO) on one specific, highly ordered lattice site. The intermediate solid-solutions, however, display increasing disorder around the Cm dopant as a result of random variations in nearest neighbor distances. In hydrated rhabdophane, and especially its La-rich solid-solutions, Cm is preferentially incorporated on nonhydrated lattice sites. This site occupancy is not in agreement with the hydrated rhabdophane structure, where two-thirds of the lattice sites are associated with water of hydration (LnPO·0.67HO), implying that structural substitution reactions cannot be predicted based on the structure of the host matrix only.