Crystallographic structure and charge distribution of AUO₄ and A₃UO₆ uranates (A = Ca, Sr, Ba or Pb)

AUO₄ and A₃UO₆ uranates (A = Ca, Sr, Ba or Pb) have been synthesized by solid state reaction. Their crystallographic structures have been studied combining Powder X-ray Diffraction (PXRD) and Extended X-ray Absorption Fine Structure (EXAFS). Depending on the nature of the alkali earth metal, the uranates compounds crystallize in different structures, in which the uranium local environment around the atoms have been identified. The U geometry has been compared to the oxidation states determined from X-ray Absorption Near Edge Spectroscopy (XANES).