DOE OSTI2020
Mg2(PO4)OH crystallizes in the monoclinic Cm space group. The structure is three-dimensional and consists of two phosphorus oxide (po) molecules and one Mg12P5H3O29 framework. In the Mg12P5H3O29 framework, 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 four MgO6 octahedra, corners with four PO4 tetrahedra, edges with two equivalent MgO6 octahedra, and a faceface with one MgO6 octahedra. The corner-sharing octahedra tilt angles range from 45–71°. There are a spread of Mg–O bond distances ranging from 2.04–2.29 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four MgO6 octahedra, corners with four PO4 tetrahedra, edges with two equivalent MgO6 octahedra, and a faceface with one MgO6 octahedra. The corner-sharing octahedra tilt angles range from 45–71°. There are a spread of Mg–O bond distances ranging from 2.04–2.29 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four MgO6 octahedra, corners with four PO4 tetrahedra, edges with two equivalent MgO6 octahedra, and a faceface with one MgO6 octahedra. The corner-sharing octahedra tilt angles range from 45–71°. There are a spread of Mg–O bond distances ranging from 2.04–2.29 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with three MgO6 octahedra, corners with three PO4 tetrahedra, edges with two equivalent MgO6 octahedra, and a faceface with one MgO6 octahedra. The corner-sharing octahedra tilt angles range from 45–61°. There are a spread of Mg–O bond distances ranging from 2.03–2.40 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with three MgO6 octahedra, corners with three PO4 tetrahedra, edges with two equivalent MgO6 octahedra, and a faceface with one MgO6 octahedra. The corner-sharing octahedra tilt angles range from 45–61°. There are a spread of Mg–O bond distances ranging from 2.03–2.40 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with three MgO6 octahedra, corners with three PO4 tetrahedra, edges with two equivalent MgO6 octahedra, and a faceface with one MgO6 octahedra. The corner-sharing octahedra tilt angles range from 45–61°. There are a spread of Mg–O bond distances ranging from 2.03–2.40 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with nine MgO6 octahedra. The corner-sharing octahedra tilt angles range from 40–70°. There is three shorter (1.55 Å) and one longer (1.57 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 45–61°. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 45–61°. There are a spread of P–O bond distances ranging from 1.54–1.56 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Mg2+ and one O2- atom. The O–O bond length is 1.55 Å. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one O2- atom. The O–O bond length is 1.55 Å. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to two equivalent Mg2+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a trigonal planar geometry to two Mg2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Mg2+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a tetrahedral geometry to three Mg2+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 5-coordinate geometry to four Mg2+ and one O2- atom. In the fourteenth O2- site, O2- is bonded in a 5-coordinate geometry to four Mg2+ and one O2- atom. In the fifteenth O2- site, O2- is bonded in a distorted single-bond geometry to four Mg2+ and one H1+ atom. In the sixteenth O2- site, O2- is bonded in a distorted single-bond geometry to four Mg2+ and one H1+ atom.