DOI: 10.17188/1280661
title: Materials Data on Ca3Mg3(PO4)4 by Materials Project

description: Ca3Mg3(PO4)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are five inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.43–2.87 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with two MgO6 octahedra, corners with four PO4 tetrahedra, a cornercorner with one MgO5 trigonal bipyramid, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 62–64°. There are a spread of Ca–O bond distances ranging from 2.24–2.46 Å. In the third Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.76 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.38–2.88 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.37–2.81 Å. There are five inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share a cornercorner with one CaO6 octahedra, corners with four PO4 tetrahedra, a cornercorner with one MgO5 trigonal bipyramid, an edgeedge with one PO4 tetrahedra, and an edgeedge with one MgO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 62°. There are a spread of Mg–O bond distances ranging from 2.02–2.27 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 CaO6 octahedra, corners with five PO4 tetrahedra, and a cornercorner with one MgO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 74°. There are a spread of Mg–O bond distances ranging from 1.99–2.12 Å. In the third Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share a cornercorner with one MgO6 octahedra, corners with five PO4 tetrahedra, a cornercorner with one MgO5 trigonal bipyramid, and an edgeedge with one MgO6 octahedra. The corner-sharing octahedral tilt angles are 70°. There are a spread of Mg–O bond distances ranging from 2.05–2.13 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share a cornercorner with one CaO6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 64°. There are a spread of Mg–O bond distances ranging from 2.04–2.28 Å. In the fifth Mg2+ site, Mg2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are two shorter (1.98 Å) and two longer (2.06 Å) Mg–O bond lengths. There are six inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CaO6 octahedra, a cornercorner with one MgO6 octahedra, and corners with three MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 49–53°. There are a spread of P–O bond distances ranging from 1.54–1.59 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two MgO6 octahedra and corners with two MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 56–63°. There are a spread of P–O bond distances ranging from 1.54–1.59 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CaO6 octahedra, corners with two MgO5 trigonal bipyramids, and an edgeedge with one MgO6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are a spread of P–O bond distances ranging from 1.54–1.58 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent MgO6 octahedra and an edgeedge with one CaO6 octahedra. The corner-sharing octahedra tilt angles range from 44–67°. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with two equivalent CaO6 octahedra, and corners with two equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 35–64°. There are a spread of P–O bond distances ranging from 1.54–1.56 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent MgO6 octahedra, a cornercorner with one MgO5 trigonal bipyramid, and an edgeedge with one MgO6 octahedra. The corner-sharing octahedra tilt angles range from 46–59°. There is three shorter (1.55 Å) and one longer (1.56 Å) P–O bond length. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Mg2+, and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Mg2+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mg2+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Mg2+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mg2+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Mg2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two Ca2+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+, one Mg2+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to two Ca2+, one 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 3-coordinate geometry to one Ca2+, one Mg2+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mg2+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Mg2+, and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a distorted T-shaped geometry to two Ca2+ and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Ca2+, one Mg2+, and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mg2+, and one P5+ atom. In the twentieth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Mg2+, and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mg2+, and one P5+ atom. In the twenty-third O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two Mg2+, and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two Mg2+, and one P5+ atom.