Materials Data on Na3UO4 by Materials Project
Na3UO4 is Caswellsilverite-like structured and crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with six equivalent NaO6 octahedra, edges with four equivalent UO6 octahedra, and edges with eight NaO6 octahedra. The corner-sharing octahedra tilt angles range from 12–15°. There are two shorter (2.36 Å) and four longer (2.47 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with six equivalent UO6 octahedra, edges with two equivalent UO6 octahedra, and edges with ten NaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. There are four shorter (2.63 Å) and two longer (2.67 Å) Na–O bond lengths. U5+ is bonded to six O2- atoms to form UO6 octahedra that share corners with six equivalent NaO6 octahedra, edges with two equivalent UO6 octahedra, and edges with ten NaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. There are two shorter (2.03 Å) and four longer (2.28 Å) U–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to five Na1+ and one U5+ atom to form a mixture of distorted edge and corner-sharing ONa5U octahedra. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded to four Na1+ and two equivalent U5+ atoms to form ONa4U2 octahedra that share corners with six equivalent ONa4U2 octahedra and edges with twelve ONa5U octahedra. The corner-sharing octahedral tilt angles are 0°.