DOE OSTI2020
La2Zr2O7 crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. there are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing LaO6 octahedra. The corner-sharing octahedral tilt angles are 75°. There are four shorter (2.40 Å) and two longer (2.43 Å) La–O bond lengths. In the second La3+ site, La3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.29–2.45 Å. There are two inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.17–2.63 Å. In the second Zr4+ site, Zr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.21–2.44 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent La3+ and two equivalent Zr4+ atoms to form OLa2Zr2 tetrahedra that share corners with fourteen OLa2Zr2 tetrahedra and edges with five OLa3Zr tetrahedra. In the second O2- site, O2- is bonded to three La3+ and one Zr4+ atom to form a mixture of distorted edge and corner-sharing OLa3Zr tetrahedra. In the third O2- site, O2- is bonded to two equivalent La3+ and two equivalent Zr4+ atoms to form OLa2Zr2 tetrahedra that share corners with fourteen OLa3Zr tetrahedra and edges with five OZr4 tetrahedra. In the fourth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted edge and corner-sharing OZr4 tetrahedra. In the fifth O2- site, O2- is bonded to one La3+ and three Zr4+ atoms to form OLaZr3 tetrahedra that share corners with fourteen OLa2Zr2 tetrahedra and edges with six OLa3Zr tetrahedra.