Materials Data on Ca3UN4 by Materials Project
Ca3UN4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six N3- atoms to form CaN6 octahedra that share corners with six CaN6 octahedra, edges with four equivalent UN6 octahedra, and edges with eight CaN6 octahedra. The corner-sharing octahedra tilt angles range from 1–22°. There are three shorter (2.49 Å) and three longer (2.50 Å) Ca–N bond lengths. In the second Ca2+ site, Ca2+ is bonded to six N3- atoms to form CaN6 octahedra that share corners with six CaN6 octahedra, edges with four equivalent UN6 octahedra, and edges with eight CaN6 octahedra. The corner-sharing octahedra tilt angles range from 1–22°. There are three shorter (2.49 Å) and three longer (2.50 Å) Ca–N bond lengths. In the third Ca2+ site, Ca2+ is bonded to six N3- atoms to form CaN6 octahedra that share corners with two equivalent UN6 octahedra, corners with four equivalent CaN6 octahedra, edges with four equivalent UN6 octahedra, and edges with eight CaN6 octahedra. The corner-sharing octahedra tilt angles range from 1–3°. There are a spread of Ca–N bond distances ranging from 2.45–2.98 Å. U6+ is bonded to six N3- atoms to form UN6 octahedra that share corners with two equivalent CaN6 octahedra, corners with four equivalent UN6 octahedra, and edges with twelve CaN6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of U–N bond distances ranging from 2.02–2.53 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded to four Ca2+ and two equivalent U6+ atoms to form a mixture of edge and corner-sharing NCa4U2 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the second N3- site, N3- is bonded in a 6-coordinate geometry to five Ca2+ and one U6+ atom. In the third N3- site, N3- is bonded to four Ca2+ and two equivalent U6+ atoms to form a mixture of edge and corner-sharing NCa4U2 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. In the fourth N3- site, N3- is bonded in a 6-coordinate geometry to five Ca2+ and one U6+ atom.