Materials Data on Na2Ca2Ta3O10 by Materials Project
Na2Ca2Ta3O10 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Na1+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–3.01 Å. Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with eight equivalent CaO12 cuboctahedra, faces with five equivalent CaO12 cuboctahedra, and faces with eight TaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.58–2.95 Å. There are three inequivalent Ta+4.67+ sites. In the first Ta+4.67+ site, Ta+4.67+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with five TaO6 octahedra and faces with four equivalent CaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–17°. There are a spread of Ta–O bond distances ranging from 1.86–2.16 Å. In the second Ta+4.67+ site, Ta+4.67+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and faces with eight equivalent CaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There is two shorter (1.97 Å) and four longer (1.99 Å) Ta–O bond length. In the third Ta+4.67+ site, Ta+4.67+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and faces with eight equivalent CaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There is two shorter (1.97 Å) and four longer (1.99 Å) Ta–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four equivalent Ca2+ and two Ta+4.67+ atoms. In the second O2- site, O2- is bonded to five equivalent Na1+ and one Ta+4.67+ atom to form a mixture of distorted corner and edge-sharing ONa5Ta octahedra. The corner-sharing octahedral tilt angles are 4°. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+, two equivalent Ca2+, and two equivalent Ta+4.67+ atoms. In the fourth O2- site, O2- is bonded in a linear geometry to four equivalent Ca2+ and two equivalent Ta+4.67+ atoms.