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DOE OSTI2020

Materials Data on Mg17(As3O16)2 by Materials Project

Mg17(As3O16)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are nine inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with five MgO6 octahedra. The corner-sharing octahedra tilt angles range from 12–22°. There are a spread of Mg–O bond distances ranging from 2.06–2.18 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three equivalent MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with five MgO6 octahedra. The corner-sharing octahedra tilt angles range from 12–22°. There are a spread of Mg–O bond distances ranging from 2.05–2.19 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedra tilt angles range from 2–13°. There are a spread of Mg–O bond distances ranging from 2.04–2.20 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent AsO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–14°. There are two shorter (2.15 Å) and four longer (2.16 Å) Mg–O bond lengths. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent AsO6 octahedra, and edges with seven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 2–22°. There are a spread of Mg–O bond distances ranging from 2.11–2.23 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent AsO6 octahedra, and edges with seven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–22°. There are a spread of Mg–O bond distances ranging from 2.10–2.24 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–15°. There are a spread of Mg–O bond distances ranging from 2.04–2.22 Å. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three equivalent MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–14°. There are a spread of Mg–O bond distances ranging from 2.06–2.17 Å. In the ninth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedra tilt angles range from 13–14°. There are a spread of Mg–O bond distances ranging from 2.02–2.20 Å. There are three inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to six O2- atoms to form AsO6 octahedra that share edges with eleven MgO6 octahedra. There are a spread of As–O bond distances ranging from 1.83–1.92 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with nine MgO6 octahedra. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of As–O bond distances ranging from 1.71–1.76 Å. In the third As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with nine MgO6 octahedra. The corner-sharing octahedra tilt angles range from 52–58°. There is three shorter (1.71 Å) and one longer (1.76 Å) As–O bond length. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded to three Mg2+ and one As5+ atom to form distorted OMg3As trigonal pyramids that share corners with five OMg5 square pyramids, a cornercorner with one OMg3As trigonal pyramid, an edgeedge with one OMg6 octahedra, and edges with three OMg4As square pyramids. In the second O2- site, O2- is bonded to three Mg2+ and one As5+ atom to form distorted OMg3As trigonal pyramids that share corners with five OMg5 square pyramids, a cornercorner with one OMg3As trigonal pyramid, an edgeedge with one OMg6 octahedra, and edges with three OMg4As square pyramids. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the seventh O2- site, O2- is bonded to four Mg2+ and one As5+ atom to form OMg4As square pyramids that share corners with five OMg4As square pyramids, edges with two equivalent OMg6 octahedra, edges with three OMg5 square pyramids, and edges with two OMg3As trigonal pyramids. In the eighth O2- site, O2- is bonded to four Mg2+ and one As5+ atom to form OMg4As square pyramids that share corners with four OMg4As square pyramids, a cornercorner with one OMg3As trigonal pyramid, an edgeedge with one OMg6 octahedra, edges with four OMg5 square pyramids, and edges with two OMg3As trigonal pyramids. In the ninth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share a cornercorner with one OMg6 octahedra, corners with two equivalent OMg5 square pyramids, edges with seven OMg4As square pyramids, and edges with two OMg3As trigonal pyramids. The corner-sharing octahedral tilt angles are 0°. In the tenth O2- site, O2- is bonded to four Mg2+ and one As5+ atom to form OMg4As square pyramids that share corners with three OMg4As square pyramids, corners with two equivalent OMg3As trigonal pyramids, edges with two equivalent OMg6 octahedra, edges with four OMg5 square pyramids, and an edgeedge with one OMg3As trigonal pyramid. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the fourteenth O2- site, O2- is bonded to five Mg2+ atoms to form OMg5 square pyramids that share corners with two equivalent OMg6 octahedra, corners with four OMg3As trigonal pyramids, and edges with five OMg4As square pyramids. The corner-sharing octahedral tilt angles are 8°. In the fifteenth O2- site, O2- is bonded to four Mg2+ and one As5+ atom to form OMg4As square pyramids that share corners with two OMg4As square pyramids, corners with three OMg3As trigonal pyramids, edges with two equivalent OMg6 octahedra, edges with four OMg5 square pyramids, and an edgeedge with one OMg3As trigonal pyramid. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg2As2O7 by Materials Project

Mg2As2O7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Mg2+ is bonded to six O2- atoms to form distorted MgO6 pentagonal pyramids that share corners with six equivalent AsO4 tetrahedra and edges with three equivalent MgO6 pentagonal pyramids. There are a spread of Mg–O bond distances ranging from 2.08–2.23 Å. As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with six equivalent MgO6 pentagonal pyramids and a cornercorner with one AsO4 tetrahedra. There are a spread of As–O bond distances ranging from 1.70–1.74 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one As5+ atom. In the second O2- site, O2- is bonded in a linear geometry to two equivalent As5+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg3(AsO4)2 by Materials Project

Mg3(AsO4)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are nine inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Mg–O bond distances ranging from 2.03–2.34 Å. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form distorted MgO5 trigonal bipyramids that share a cornercorner with one MgO5 trigonal bipyramid, an edgeedge with one AsO6 octahedra, and an edgeedge with one MgO5 trigonal bipyramid. There are a spread of Mg–O bond distances ranging from 2.01–2.16 Å. In the third Mg2+ site, Mg2+ is bonded to five O2- atoms to form distorted corner-sharing MgO5 trigonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.94–2.04 Å. In the fourth Mg2+ site, Mg2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Mg–O bond distances ranging from 2.01–2.52 Å. In the fifth Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 2.13–2.53 Å. In the sixth Mg2+ site, Mg2+ is bonded to five O2- atoms to form distorted edge-sharing MgO5 trigonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.99–2.29 Å. In the seventh Mg2+ site, Mg2+ is bonded to five O2- atoms to form distorted MgO5 tetrahedra that share a cornercorner with one AsO6 octahedra and a cornercorner with one MgO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 10°. There are a spread of Mg–O bond distances ranging from 1.92–2.71 Å. In the eighth Mg2+ site, Mg2+ is bonded to five O2- atoms to form distorted MgO5 tetrahedra that share an edgeedge with one AsO6 octahedra. There are a spread of Mg–O bond distances ranging from 1.92–2.39 Å. In the ninth Mg2+ site, Mg2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Mg–O bond distances ranging from 1.94–2.17 Å. There are six inequivalent As5+ sites. In the first As5+ site, As5+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There are a spread of As–O bond distances ranging from 1.79–1.85 Å. In the second As5+ site, As5+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of As–O bond distances ranging from 1.76–1.91 Å. In the third As5+ site, As5+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of As–O bond distances ranging from 1.79–2.20 Å. In the fourth As5+ site, As5+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of As–O bond distances ranging from 1.72–2.36 Å. In the fifth As5+ site, As5+ is bonded to six O2- atoms to form distorted AsO6 octahedra that share a cornercorner with one MgO5 tetrahedra, an edgeedge with one MgO5 tetrahedra, and an edgeedge with one MgO5 trigonal bipyramid. There are a spread of As–O bond distances ranging from 1.82–2.25 Å. In the sixth As5+ site, As5+ is bonded in a distorted water-like geometry to three O2- atoms. There are a spread of As–O bond distances ranging from 1.74–2.49 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Mg2+ and one As5+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Mg2+ and two As5+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to three Mg2+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one As5+ and one O2- atom. The O–O bond length is 1.50 Å. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Mg2+, one As5+, and one O2- atom. The O–O bond length is 1.50 Å. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Mg2+ and one O2- atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+, one As5+, and one O2- atom. The O–O bond length is 1.50 Å. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one O2- atom. In the ninth O2- site, O2- is bonded in a trigonal planar geometry to two Mg2+ and one As5+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one As5+ atom. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to two Mg2+ and one As5+ atom. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted T-shaped geometry to two Mg2+ and one As5+ atom. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Mg2+, one As5+, and one O2- atom. The O–O bond length is 1.50 Å. In the sixteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Mg2+ and one O2- atom. In the seventeenth O2- site, O2- is bonded in a 4-coordinate geometry to three Mg2+ and one O2- atom. The O–O bond length is 1.50 Å. In the eighteenth O2- site, O2- is bonded in a trigonal planar geometry to two Mg2+ and one As5+ atom. In the nineteenth O2- site, O2- is bonded in a trigonal non-coplanar geometry to two Mg2+ and one As5+ atom. In the twentieth O2- site, O2- is bonded in a 4-coordinate geometry to two Mg2+ and two As5+ atoms. In the twenty-first O2- site, O2- is bonded in a 1-coordinate geometry to one Mg2+, one As5+, and one O2- atom. In the twenty-second O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one As5+ atom. In the twenty-third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the twenty-fourth O2- site, O2- is bonded in a 2-coordinate geometry to two Mg2+, one As5+, and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg3(AsO4)2 by Materials Project

Mg3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent AsO4 tetrahedra, corners with two equivalent MgO5 trigonal bipyramids, and edges with two equivalent MgO5 trigonal bipyramids. There are a spread of Mg–O bond distances ranging from 2.06–2.20 Å. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share a cornercorner with one MgO6 octahedra, corners with three equivalent AsO4 tetrahedra, an edgeedge with one MgO6 octahedra, an edgeedge with one AsO4 tetrahedra, and an edgeedge with one MgO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 51°. There are a spread of Mg–O bond distances ranging from 2.00–2.16 Å. As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with three equivalent MgO6 octahedra, corners with three equivalent MgO5 trigonal bipyramids, and an edgeedge with one MgO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 39–54°. There are a spread of As–O bond distances ranging from 1.71–1.73 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one As5+ atom. In the third O2- site, O2- is bonded in a T-shaped geometry to two Mg2+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg17(As3O16)2 by Materials Project

Mg17(As3O16)2 crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are six inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three equivalent MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedra tilt angles range from 3–17°. There are a spread of Mg–O bond distances ranging from 2.05–2.18 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share a cornercorner with one MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are a spread of Mg–O bond distances ranging from 2.08–2.16 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedral tilt angles are 16°. There are a spread of Mg–O bond distances ranging from 2.00–2.20 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three equivalent MgO6 octahedra, corners with three AsO4 tetrahedra, an edgeedge with one AsO6 octahedra, and edges with five MgO6 octahedra. The corner-sharing octahedra tilt angles range from 8–18°. There are a spread of Mg–O bond distances ranging from 2.06–2.17 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two AsO6 octahedra, and edges with seven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 3–18°. There are a spread of Mg–O bond distances ranging from 2.08–2.28 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent AsO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–16°. There are two shorter (2.13 Å) and four longer (2.17 Å) Mg–O bond lengths. There are four inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with nine MgO6 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of As–O bond distances ranging from 1.70–1.77 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with nine MgO6 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of As–O bond distances ranging from 1.70–1.75 Å. In the third As5+ site, As5+ is bonded to six O2- atoms to form AsO6 octahedra that share edges with ten MgO6 octahedra. There is four shorter (1.87 Å) and two longer (1.90 Å) As–O bond length. In the fourth As5+ site, As5+ is bonded to six O2- atoms to form AsO6 octahedra that share edges with twelve MgO6 octahedra. There is four shorter (1.87 Å) and two longer (1.89 Å) As–O bond length. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded to four Mg2+ and one As5+ atom to form OMg4As square pyramids that share corners with three OMg4As square pyramids, corners with two equivalent OMg3As trigonal pyramids, edges with two equivalent OMg6 octahedra, edges with five OMg5 square pyramids, and an edgeedge with one OMg3As trigonal pyramid. In the second O2- site, O2- is bonded to three Mg2+ and one As5+ atom to form distorted OMg3As trigonal pyramids that share corners with two equivalent OMg6 octahedra, a cornercorner with one OMg5 square pyramid, and edges with three OMg4As square pyramids. The corner-sharing octahedral tilt angles are 3°. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share a cornercorner with one OMg6 octahedra, corners with two equivalent OMg5 square pyramids, corners with two equivalent OMg3As trigonal pyramids, edges with seven OMg4As square pyramids, and edges with two equivalent OMg3As trigonal pyramids. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to four Mg2+ and one As5+ atom to form OMg4As square pyramids that share corners with four OMg4As square pyramids, a cornercorner with one OMg3As trigonal pyramid, edges with two equivalent OMg6 octahedra, edges with five OMg5 square pyramids, and an edgeedge with one OMg3As trigonal pyramid. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one As5+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one As5+ atom. In the eighth O2- site, O2- is bonded to three Mg2+ and one As5+ atom to form OMg3As trigonal pyramids that share corners with four OMg5 square pyramids, corners with two equivalent OMg3As trigonal pyramids, an edgeedge with one OMg6 octahedra, edges with two equivalent OMg4As square pyramids, and an edgeedge with one OMg3As trigonal pyramid. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one As5+ atom. In the tenth O2- site, O2- is bonded to five Mg2+ atoms to form OMg5 square pyramids that share corners with two equivalent OMg6 octahedra, corners with five OMg3As trigonal pyramids, and edges with five OMg4As square pyramids. The corner-sharing octahedral tilt angles are 10°. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the twelfth O2- site, O2- is bonded to four Mg2+ and one As5+ atom to form OMg4As square pyramids that share corners with five OMg4As square pyramids, an edgeedge with one OMg6 octahedra, edges with two equivalent OMg5 square pyramids, and edges with four equivalent OMg3As trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg3(AsO4)2 by Materials Project

Mg3(AsO4)2 crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two MgO6 octahedra, corners with four AsO4 tetrahedra, edges with two MgO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–60°. There are a spread of Mg–O bond distances ranging from 2.03–2.21 Å. In the second Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.16 Å) and four longer (2.66 Å) Mg–O bond lengths. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with six AsO4 tetrahedra, and edges with two equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 60°. There are a spread of Mg–O bond distances ranging from 2.08–2.15 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with six AsO4 tetrahedra, and edges with two equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 55°. There are a spread of Mg–O bond distances ranging from 2.07–2.23 Å. There are three inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four equivalent O2- atoms to form AsO4 tetrahedra that share corners with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 49–51°. All As–O bond lengths are 1.72 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with six MgO6 octahedra and an edgeedge with one MgO6 octahedra. The corner-sharing octahedra tilt angles range from 43–53°. There are a spread of As–O bond distances ranging from 1.70–1.78 Å. In the third As5+ site, As5+ is bonded to four equivalent O2- atoms to form AsO4 tetrahedra that share corners with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 48–51°. All As–O bond lengths are 1.72 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Mg2+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the third O2- site, O2- is bonded to three Mg2+ and one As5+ atom to form corner-sharing OMg3As tetrahedra. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg3(AsO4)2 by Materials Project

Mg3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with five AsO4 tetrahedra, a cornercorner with one MgO5 trigonal bipyramid, and an edgeedge with one MgO5 trigonal bipyramid. There are a spread of Mg–O bond distances ranging from 2.02–2.09 Å. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with five AsO4 tetrahedra, a cornercorner with one MgO5 trigonal bipyramid, and an edgeedge with one MgO5 trigonal bipyramid. There are a spread of Mg–O bond distances ranging from 1.98–2.13 Å. In the third Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 2.03–2.71 Å. There are two inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with five MgO5 trigonal bipyramids. There is two shorter (1.72 Å) and two longer (1.73 Å) As–O bond length. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with five MgO5 trigonal bipyramids. There are a spread of As–O bond distances ranging from 1.70–1.74 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Mg2+ and one As5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to two Mg2+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one As5+ atom. In the eighth O2- site, O2- is bonded in a trigonal planar geometry to two Mg2+ and one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg3(AsO4)2 by Materials Project

Mg3(AsO4)2 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent AsO4 tetrahedra and edges with four MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.02–2.20 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent AsO4 tetrahedra and edges with four equivalent MgO6 octahedra. There are two shorter (2.08 Å) and four longer (2.13 Å) Mg–O bond lengths. As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with nine MgO6 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There is three shorter (1.72 Å) and one longer (1.78 Å) As–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one As5+ atom. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one As5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg2As2O9 by Materials Project

Mg2As2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with five AsO4 tetrahedra and edges with two equivalent MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.04–2.14 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with five AsO4 tetrahedra and edges with two equivalent MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.01–2.14 Å. There are two inequivalent As sites. In the first As site, As is bonded to four O atoms to form AsO4 tetrahedra that share corners with five MgO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–59°. There are a spread of As–O bond distances ranging from 1.68–1.80 Å. In the second As site, As is bonded to four O atoms to form AsO4 tetrahedra that share corners with five MgO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–60°. There are a spread of As–O bond distances ranging from 1.66–1.80 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Mg and one As atom. In the second O site, O is bonded in a distorted trigonal planar geometry to two Mg and one As atom. In the third O site, O is bonded in a trigonal planar geometry to two Mg and one As atom. In the fourth O site, O is bonded in a single-bond geometry to one Mg atom. In the fifth O site, O is bonded in a distorted trigonal planar geometry to two Mg and one As atom. In the sixth O site, O is bonded in a single-bond geometry to one Mg atom. In the seventh O site, O is bonded in a bent 120 degrees geometry to one Mg and one As atom. In the eighth O site, O is bonded in a distorted trigonal planar geometry to two Mg and one As atom. In the ninth O site, O is bonded in a bent 120 degrees geometry to two As atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg2AsO5 by Materials Project

Mg2AsO5 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four equivalent AsO4 tetrahedra, corners with four equivalent MgO5 trigonal bipyramids, and edges with two equivalent MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.06–2.19 Å. In the second Mg site, Mg is bonded to five O atoms to form distorted MgO5 trigonal bipyramids that share corners with four equivalent MgO6 octahedra, corners with four equivalent AsO4 tetrahedra, and an edgeedge with one MgO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 50–65°. There are a spread of Mg–O bond distances ranging from 2.00–2.06 Å. As is bonded to four O atoms to form AsO4 tetrahedra that share corners with four equivalent MgO6 octahedra and corners with four equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 54–65°. All As–O bond lengths are 1.72 Å. There are four inequivalent O sites. In the first O site, O is bonded in a trigonal planar geometry to two equivalent Mg and one As atom. In the second O site, O is bonded in a distorted trigonal planar geometry to three Mg atoms. In the third O site, O is bonded in a trigonal planar geometry to two equivalent Mg and one As atom. In the fourth O site, O is bonded in a trigonal planar geometry to two Mg and one As atom.

36 MATERIALS SCIENCE↗