Materials Data on La2Hf2O7 by Materials Project
La2Hf2O7 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. La3+ is bonded to eight O2- atoms to form distorted LaO8 hexagonal bipyramids that share edges with six equivalent LaO8 hexagonal bipyramids and edges with six equivalent HfO6 octahedra. There are two shorter (2.34 Å) and six longer (2.65 Å) La–O bond lengths. Hf4+ is bonded to six equivalent O2- atoms to form HfO6 octahedra that share corners with six equivalent HfO6 octahedra and edges with six equivalent LaO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 49°. All Hf–O bond lengths are 2.10 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent La3+ atoms to form corner-sharing OLa4 tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent La3+ and two equivalent Hf4+ atoms.