Synthesis and characterization of homogeneous (U,Am)O₂ and (U,Pu,Am)O₂ nanopowders

Abstract

Sinterable homogeneous nanoparticles of [U,(Pu),Am]O2 are produced hydrothermally from corresponding oxalates. The uranium and americium oxidation states are diverse in both as-synthesized nanopowders and sintered materials.

Synthesis, Characterization, and Stability of Two Americium Vanadates, AmVO3 and AmVO4

“…The main absorption maximum was set to 3890 eV for AmO 2 . 14 The maxima of the WLs are located at AmCl 6 3− (3888.4 eV), AmFe 2 (3887.5 eV) reported elsewhere. 15,16 Both Am M 5 edge data cited above were measured in conventional fluorescence mode and were similar to AmVO 3 and AmVO 4 (3888.5 eV) recorded in this work.…”

Grain growth of NpO2 and UO2 nanocrystals

“…12 The process was reported for the rst time by Walter et al 11 and has already been applied in several studies. 12,15,28 In summary, the oxalates (U(C 2 O 4 ) 2 $6H 2 O and Np(C 2 O 4 ) 2 $6H 2 O), were directly precipitated from a U(IV) solution (0.47 M, obtained by electroreduction of a UO 2 (NO 3 ) 2 solution in 4 M HNO 3 with 0.5 M hydrazine) and from a Np(IV) solution (0.6 M in about 2 M HNO 3 ) with excess of 0.5 M oxalic acid. The oxalic acid dihydrate was supplied by Merck in analytical grade.…”

Ultrasonically controlled synthesis of UO2+xcolloidal nanoparticles

“…and their subsequent mobility have been highly reported in the literature. 6,[18][19][20] U(IV) also shows a strong Lewis acid behaviour depending on the pH conditions of the aqueous media which results in the hydrolysis properties according to eqn (1). 21 Intrinsic U(IV) colloids resulting from the condensation of the as-formed hydrolysed species represent another potential source of mobility for the radioactivity and should be taken into account to correctly estimate their behaviour in an environmental context (speciation, solubility, reactivity, redox, etc.).…”

“…31 Recently, the approach allowed the group to successfully propose homogeneous NPs of mixed oxides (U,Pu)O 2 , (U,Am)O 2 and (U,Pu,Am)O 2 . 1,33 Also, the recent work of Tabata et al showed the formation of UO 2+x nanoparticles under hydrothermal treatment (100-450 °C) from U(IV) or U(VI) nitrates in the presence of organic additives (ethanol, aldehyde, carbonate, etc.). 34,35 The experimental conditions have an influence on the size, crystallinity and shape of the NPs, which can be spherical or rectangular.…”

“…Increasing attention is especially given to the preparation and characterization of actinide nanomaterials whose nanoscale properties could improve, for instance, the preparation, flowing, burning and reprocessing of nuclear fuel. 1,2 At the same time, producing nuclear electricity requires ensuring the safety of the spent fuel under surface or deep underground storage. One of the major concerns deals with the corrosion and subsequent leaching of radionuclides when water comes into contact with nuclear wastes.…”