Materials Data on SrTa2O7 by Materials Project
SrTa2O7 crystallizes in the tetragonal P4/mmm space group. The structure is two-dimensional and consists of one SrTa2O7 sheet oriented in the (0, 0, 1) direction. Sr is bonded to twelve O atoms to form SrO12 cuboctahedra that share corners with four equivalent SrO12 cuboctahedra, faces with four equivalent SrO12 cuboctahedra, and faces with eight equivalent TaO6 octahedra. There are eight shorter (2.71 Å) and four longer (2.82 Å) Sr–O bond lengths. Ta is bonded to six O atoms to form TaO6 octahedra that share corners with five equivalent TaO6 octahedra and faces with four equivalent SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–13°. There are a spread of Ta–O bond distances ranging from 1.90–2.05 Å. There are three inequivalent O sites. In the first O site, O is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr and two equivalent Ta atoms. In the second O site, O is bonded in a single-bond geometry to one Ta atom. In the third O site, O is bonded in a distorted linear geometry to four equivalent Sr and two equivalent Ta atoms.