DOE OSTI2020
Na3Sr7Ti7Ta3O30 is (Cubic) Perovskite-derived structured and crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to twelve O2- atoms to form NaO12 cuboctahedra that share corners with four NaO12 cuboctahedra, corners with eight SrO12 cuboctahedra, faces with three NaO12 cuboctahedra, faces with three SrO12 cuboctahedra, faces with four TiO6 octahedra, and faces with four TaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.68–2.96 Å. In the second Na1+ site, Na1+ is bonded to twelve O2- atoms to form distorted NaO12 cuboctahedra that share corners with six NaO12 cuboctahedra, corners with six SrO12 cuboctahedra, a faceface with one SrO12 cuboctahedra, faces with five NaO12 cuboctahedra, faces with two equivalent TiO6 octahedra, and faces with six TaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.61–3.10 Å. In the third Na1+ site, Na1+ is bonded to twelve O2- atoms to form distorted NaO12 cuboctahedra that share corners with six NaO12 cuboctahedra, corners with six SrO12 cuboctahedra, faces with two SrO12 cuboctahedra, faces with four NaO12 cuboctahedra, faces with two equivalent TiO6 octahedra, and faces with six TaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.64–3.04 Å. There are seven inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with four SrO12 cuboctahedra, corners with eight NaO12 cuboctahedra, faces with three NaO12 cuboctahedra, faces with three SrO12 cuboctahedra, faces with four TiO6 octahedra, and faces with four TaO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.70–2.85 Å. In the second Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with two equivalent NaO12 cuboctahedra, corners with ten SrO12 cuboctahedra, a faceface with one NaO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.70–2.91 Å. In the third Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.71–2.89 Å. In the fourth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with two equivalent NaO12 cuboctahedra, corners with ten SrO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.67–2.91 Å. In the fifth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.71–2.88 Å. In the sixth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with four NaO12 cuboctahedra, corners with eight SrO12 cuboctahedra, a faceface with one NaO12 cuboctahedra, faces with five SrO12 cuboctahedra, faces with two equivalent TaO6 octahedra, and faces with six TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.73–2.85 Å. In the seventh Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with four NaO12 cuboctahedra, corners with eight SrO12 cuboctahedra, a faceface with one NaO12 cuboctahedra, faces with five SrO12 cuboctahedra, faces with two equivalent TaO6 octahedra, and faces with six TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.69–2.88 Å. There are seven inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one TaO6 octahedra, corners with five TiO6 octahedra, faces with two equivalent NaO12 cuboctahedra, and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–11°. There are a spread of Ti–O bond distances ranging from 1.85–2.14 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with eight SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–7°. There are a spread of Ti–O bond distances ranging from 1.88–2.09 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with eight SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–8°. There are a spread of Ti–O bond distances ranging from 1.89–2.09 Å. In the fourth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one TaO6 octahedra, corners with five TiO6 octahedra, faces with two equivalent NaO12 cuboctahedra, and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are a spread of Ti–O bond distances ranging from 1.89–2.07 Å. In the fifth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and faces with eight SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 2–6°. There are a spread of Ti–O bond distances ranging from 1.89–2.06 Å. In the sixth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with three TiO6 octahedra, corners with three TaO6 octahedra, faces with four NaO12 cuboctahedra, and faces with four SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Ti–O bond distances ranging from 1.93–2.04 Å. In the seventh Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one TaO6 octahedra, corners with five TiO6 octahedra, and faces with eight SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 2–5°. There are a spread of Ti–O bond distances ranging from 1.91–2.07 Å. There are three inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three TiO6 octahedra, corners with three TaO6 octahedra, faces with four NaO12 cuboctahedra, and faces with four SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Ta–O bond distances ranging from 1.98–2.00 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two TiO6 octahedra, corners with four TaO6 octahedra, faces with two equivalent SrO12 cuboctahedra, and faces with six NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–9°. There are a spread of Ta–O bond distances ranging from 1.92–2.07 Å. In the third Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share a cornercorner with one TiO6 octahedra, corners with five TaO6 octahedra, faces with two equivalent SrO12 cuboctahedra, and faces with six NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Ta–O bond distances ranging from 1.97–2.00 Å. There are thirty inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to one Na1+, three Sr2+, and two equivalent Ti4+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to three Na1+, one Sr2+, and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to three Na1+, one Sr2+, and two equivalent Ta5+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+, two equivalent Sr2+, and two Ti4+ atoms. In the sixth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Na1+, two equivalent Sr2+, one Ti4+, and one Ta5+ atom. In the seventh O2- site, O2- is bonded in a 6-coordinate geometry to four Sr2+ and two Ti4+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+, two equivalent Sr2+, one Ti4+, and one Ta5+ atom. In the ninth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the tenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the eleventh O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the twelfth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Na1+, two equivalent Sr2+, one Ti4+, and one Ta5+ atom. In the seventeenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+, one Ti4+, and one Ta5+ atom. In the eighteenth O2- site, O2- is bonded in a distorted linear geometry to four Na1+ and two Ta5+ atoms. In the nineteenth O2- site, O2- is bonded in a distorted linear geometry to four Na1+ and two Ta5+ atoms. In the twentieth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Na1+, two equivalent Sr2+, one Ti4+, and one Ta5+ atom. In the twenty-first O2- site, O2- is bonded to four Na1+, one Ti4+, and one Ta5+ atom to form distorted ONa4TaTi octahedra that share edges with two equivalent ONa4TaTi octahedra and faces with two equivalent ONa2Sr2Ti2 octahedra. In the twenty-second O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Ti4+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted linear geometry to two equivalent Na1+, two equivalent Sr2+, and two Ta5+ atoms. In the twenty-fourth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms. In the twenty-fifth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms. In the twenty-sixth O2- site, O2- is bonded in a distorted linear geometry to one Na1+, three Sr2+, and two equivalent Ti4+ atoms. In the twenty-seventh O2- site, O2- is bonded to two Na1+, two Sr2+, and two equivalent Ti4+ atoms to form distorted ONa2Sr2Ti2 octahedra that share corners with two equivalent ONa2Sr2Ti2 octahedra and faces with two equivalent ONa4TaTi octahedra. The corner-sharing octahedral tilt angles are 0°. In the twenty-eighth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms. In the twenty-ninth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms. In the thirtieth O2- site, O2- is bonded in a distorted linear geometry to two Na1+, two Sr2+, and two equivalent Ta5+ atoms.