DOE OSTI2020
NaEuO2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two equivalent EuO6 octahedra, corners with four equivalent NaO6 octahedra, edges with four equivalent NaO6 octahedra, and edges with eight equivalent EuO6 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. There are four shorter (2.39 Å) and two longer (2.98 Å) Na–O bond lengths. Eu3+ is bonded to six O2- atoms to form EuO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with four equivalent EuO6 octahedra, edges with four equivalent EuO6 octahedra, and edges with eight equivalent NaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. There are two shorter (2.34 Å) and four longer (2.39 Å) Eu–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent Na1+ and three equivalent Eu3+ atoms to form a mixture of distorted edge and corner-sharing ONa3Eu3 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. There are two shorter (2.39 Å) and one longer (2.98 Å) O–Na bond lengths. In the second O2- site, O2- is bonded to three equivalent Na1+ and three equivalent Eu3+ atoms to form a mixture of distorted edge and corner-sharing ONa3Eu3 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. In the third O2- site, O2- is bonded to three equivalent Na1+ and three equivalent Eu3+ atoms to form a mixture of distorted edge and corner-sharing ONa3Eu3 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. In the fourth O2- site, O2- is bonded to three equivalent Na1+ and three equivalent Eu3+ atoms to form a mixture of distorted edge and corner-sharing ONa3Eu3 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. There are one shorter (2.34 Å) and two longer (2.39 Å) O–Eu bond lengths.