Highly crystalline UO_(2)nanoparticles(NPs)with sizes of 2–3 nm were produced by fast chemical deposition of uranium(IV)under reducing conditions at pH 8–11.The particles were then characterized by microscopy and sp...Highly crystalline UO_(2)nanoparticles(NPs)with sizes of 2–3 nm were produced by fast chemical deposition of uranium(IV)under reducing conditions at pH 8–11.The particles were then characterized by microscopy and spectroscopy techniques including high-resolution transmission electron microscopy(HRTEM),X-ray diffraction(XRD),high-energy resolution fluorescence detection(HERFD)X-ray absorption spectroscopy at the U M_(4)edge and extended X-ray absorption fine structure(EXAFS)spectroscopy at the U L_(3)edge.The results of this investigation show that despite U(IV)being the dominant oxidation state of the freshly prepared UO_(2)NPs,they oxidize to U_(4)O_(9)with time and under the X-ray beam,indicating the high reactivity of U(IV)under these conditions.Moreover,it was found that the oxidation process of NPs is accompanied by their growth in size to 6 nm.We highlight here the major differences and similarities of the UO_(2)NP properties to PuO_(2),ThO_(2)and CeO_(2)NPs.展开更多
基金funded by the European Commission Council under ERC[grant no.759696]support from RFBR(projectnumber no.19-33-90127)+1 种基金support by the Russian Ministry of Science and Education under grant no.075-15-2019-1891support from the Swedish Research Council(grant 2017-06465).
文摘Highly crystalline UO_(2)nanoparticles(NPs)with sizes of 2–3 nm were produced by fast chemical deposition of uranium(IV)under reducing conditions at pH 8–11.The particles were then characterized by microscopy and spectroscopy techniques including high-resolution transmission electron microscopy(HRTEM),X-ray diffraction(XRD),high-energy resolution fluorescence detection(HERFD)X-ray absorption spectroscopy at the U M_(4)edge and extended X-ray absorption fine structure(EXAFS)spectroscopy at the U L_(3)edge.The results of this investigation show that despite U(IV)being the dominant oxidation state of the freshly prepared UO_(2)NPs,they oxidize to U_(4)O_(9)with time and under the X-ray beam,indicating the high reactivity of U(IV)under these conditions.Moreover,it was found that the oxidation process of NPs is accompanied by their growth in size to 6 nm.We highlight here the major differences and similarities of the UO_(2)NP properties to PuO_(2),ThO_(2)and CeO_(2)NPs.
