“…For example, anhydrous uranyl oxides of the family UO 2 XO 4 with X ¼ S; Cr, Se, Mo and W are well known [18][19][20][21] and adopt the same crystal structure which results from the association of (UO 2 )O 5 pentagonal bipyramids sharing four equatorial oxygen atoms with different XO 4 tetrahedra, the last equatorial oxygen atom being shared with an apical oxygen atom of a neighboring (UO 2 )O 5 bipyramid. During the study of the UO 2 -WO 3 system, four phases U(WO 4 ) 2 , UW 3 O 11 , UW 4 O 14 and UW 5 O 17 have been identified by X-ray powder diffraction and high resolution electron microscopy [22].…”