Materials Data on Li2CaTa2O7 by Materials Project

Abstract

Li2CaTa2O7 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Li1+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All Li–O bond lengths are 2.09 Å. Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with four equivalent CaO12 cuboctahedra, faces with four equivalent CaO12 cuboctahedra, and faces with eight equivalent TaO6 octahedra. There are eight shorter (2.71 Å) and four longer (2.80 Å) Ca–O bond lengths. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with five equivalent TaO6 octahedra and faces with four equivalent CaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–13°. There are a spread of Ta–O bond distances ranging from 1.91–2.08 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ca2+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded to four equivalent Li1+ and one Ta5+ atom to form a mixture of distorted edge and corner-sharing OLi4Ta trigonal bipyramids. In the third O2- site, O2- is bonded in a distorted linear geometry to four equivalent Ca2+ and two equivalent Ta5+ atoms.