نتایج جستجو برای: u3o8
تعداد نتایج: 69 فیلتر نتایج به سال:
Two types of ammonium uranyl nitrate (NH4)2UO2(NO3)4·2H2O and NH4UO2(NO3)3, were thermally decomposed and reduced in a TG-DTA unit in nitrogen, air, and hydrogen atmospheres. Various intermediate phases produced by the thermal decomposition and reduction process were investigated by an X-ray diffraction analysis and a TG/DTA analysis. Both (NH4)2UO2(NO3)4·2H2O and NH4UO2(NO3)3 decomposed to amo...
Uranium oxides are fascinating materials not only owing to their technological significance in nuclear fuel applications [1] but also with respect to their dynamical properties [2], valence orbital configuration [3] and elementary excitations [4]. Understanding of the electronic, magnetic and crystal structural properties of uranium dioxide (UO2) was advanced significantly [5,6] after establish...
A new high-pressure phase of U3O8, which has a fluorite-type structure, forms at pressures greater than 8.1 GPa that was confirmed by in situ x-ray diffraction (XRD) measurements. The fluorite-type U3O8 is stable at pressures at least up to 40 GPa and temperatures to 1700 K, and quenchable to ambient conditions. Based on the XRD analysis, there is a huge volume collapse (420%) for U3O8 during t...
X-ray absorption and resonant X-ray emission measurements at the O 1s edge of the uranium oxides UO2, U3O8 and UO3 are presented. The spectral shapes of the O Kα X-ray emission spectra of UO3 exhibit significant excitation energy dependence, from an asymmetric to a symmetric form, which differs from those of UO2 and U3O8. This energy dependence is attributed to a significant difference in the o...
We show that plane wave ultrasoft pseudopotential methods readily extend to the calculation of the structural properties of lanthanide and actinide containing compounds. This is demonstrated through a series of calculations performed on UO, UO2, UO3, U3O8, UC2, alpha-CeC2, CeB6, CeSe, CeO2, NdB6, TmOI, LaBi, LaTiO3, YbO, and elemental Lu.
Albitite-type uranium deposits are widely distributed, usually of low grade (<1% U3O8), but are often large and collectively contain over 1 million tonnes of U3O8. Uranium is hosted in a wide range of metamorphic lithologies, whose only common characteristic is that they have been extensively mylonitised. Ore minerals are disseminated and rarely in megascopic veins, within and adjacent to albit...
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