DOE OSTI2020
Na2Al2(SiO4)3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Na sites. In the first Na site, Na is bonded to six O atoms to form distorted NaO6 pentagonal pyramids that share corners with two AlO4 tetrahedra, corners with two SiO4 tetrahedra, edges with two equivalent NaO6 pentagonal pyramids, an edgeedge with one AlO4 tetrahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.36–2.62 Å. In the second Na site, Na is bonded to six O atoms to form distorted NaO6 pentagonal pyramids that share corners with two AlO4 tetrahedra, corners with two SiO4 tetrahedra, edges with two equivalent NaO6 pentagonal pyramids, an edgeedge with one AlO4 tetrahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.36–2.62 Å. In the third Na site, Na is bonded to six O atoms to form distorted NaO6 pentagonal pyramids that share corners with two AlO4 tetrahedra, corners with two SiO4 tetrahedra, edges with two equivalent NaO6 pentagonal pyramids, an edgeedge with one AlO4 tetrahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.35–2.59 Å. In the fourth Na site, Na is bonded to six O atoms to form distorted NaO6 pentagonal pyramids that share corners with two AlO4 tetrahedra, corners with two SiO4 tetrahedra, edges with two equivalent NaO6 pentagonal pyramids, an edgeedge with one AlO4 tetrahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.36–2.66 Å. There are four inequivalent Al sites. In the first Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share corners with two NaO6 pentagonal pyramids, corners with four SiO4 tetrahedra, and an edgeedge with one NaO6 pentagonal pyramid. There are a spread of Al–O bond distances ranging from 1.75–1.77 Å. In the second Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share corners with two NaO6 pentagonal pyramids, corners with four SiO4 tetrahedra, and an edgeedge with one NaO6 pentagonal pyramid. There is three shorter (1.76 Å) and one longer (1.77 Å) Al–O bond length. In the third Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share corners with two NaO6 pentagonal pyramids, corners with four SiO4 tetrahedra, and an edgeedge with one NaO6 pentagonal pyramid. There is two shorter (1.76 Å) and two longer (1.77 Å) Al–O bond length. In the fourth Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share corners with two NaO6 pentagonal pyramids, corners with four SiO4 tetrahedra, and an edgeedge with one NaO6 pentagonal pyramid. There is two shorter (1.76 Å) and two longer (1.77 Å) Al–O bond length. There are six inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two AlO4 tetrahedra and corners with two SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.64 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two AlO4 tetrahedra and corners with two SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.64 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two NaO6 pentagonal pyramids, a cornercorner with one SiO4 tetrahedra, corners with three AlO4 tetrahedra, and an edgeedge with one NaO6 pentagonal pyramid. There are a spread of Si–O bond distances ranging from 1.63–1.65 Å. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two NaO6 pentagonal pyramids, a cornercorner with one SiO4 tetrahedra, corners with three AlO4 tetrahedra, and an edgeedge with one NaO6 pentagonal pyramid. There are a spread of Si–O bond distances ranging from 1.63–1.65 Å. In the fifth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two NaO6 pentagonal pyramids, a cornercorner with one SiO4 tetrahedra, corners with three AlO4 tetrahedra, and an edgeedge with one NaO6 pentagonal pyramid. There are a spread of Si–O bond distances ranging from 1.63–1.65 Å. In the sixth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two NaO6 pentagonal pyramids, a cornercorner with one SiO4 tetrahedra, corners with three AlO4 tetrahedra, and an edgeedge with one NaO6 pentagonal pyramid. There are a spread of Si–O bond distances ranging from 1.63–1.65 Å. There are twenty-four inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. In the second O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. In the third O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. In the fourth O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. In the fifth O site, O is bonded in a 4-coordinate geometry to two Na, one Al, and one Si atom. In the sixth O site, O is bonded in a 2-coordinate geometry to two Na, one Al, and one Si atom. In the seventh O site, O is bonded in a 4-coordinate geometry to two Na, one Al, and one Si atom. In the eighth O site, O is bonded in a 4-coordinate geometry to two Na, one Al, and one Si atom. In the ninth O site, O is bonded in a distorted trigonal planar geometry to one Na, one Al, and one Si atom. In the tenth O site, O is bonded in a distorted trigonal planar geometry to one Na, one Al, and one Si atom. In the eleventh O site, O is bonded in a distorted trigonal planar geometry to one Na, one Al, and one Si atom. In the twelfth O site, O is bonded in a distorted trigonal planar geometry to one Na, one Al, and one Si atom. In the thirteenth O site, O is bonded in a 3-coordinate geometry to one Na, one Al, and one Si atom. In the fourteenth O site, O is bonded in a 3-coordinate geometry to one Na, one Al, and one Si atom. In the fifteenth O site, O is bonded in a 3-coordinate geometry to one Na, one Al, and one Si atom. In the sixteenth O site, O is bonded in a distorted trigonal planar geometry to one Na, one Al, and one Si atom. In the seventeenth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the eighteenth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the nineteenth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the twentieth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the twenty-first O site, O is bonded in a water-like geometry to two Na atoms. In the twenty-second O site, O is bonded in a water-like geometry to two Na atoms. In the twenty-third O site, O is bonded in a water-like geometry to two Na atoms. In the twenty-fourth O site, O is bonded in a water-like geometry to two Na atoms.