DOI: 10.17188/1655727
title: Materials Data on Ca5Si(PO6)2 by Materials Project

description: Ca5(PO4)2SiO4 crystallizes in the orthorhombic P2_12_12_1 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 2.38–2.96 Å. In the second Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted CaO7 pentagonal bipyramids that share a cornercorner with one CaO7 pentagonal bipyramid, a cornercorner with one SiO4 tetrahedra, corners with two equivalent PO4 tetrahedra, an edgeedge with one CaO7 pentagonal bipyramid, an edgeedge with one SiO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.30–2.60 Å. In the third Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted CaO7 pentagonal bipyramids that share a cornercorner with one CaO7 pentagonal bipyramid, a cornercorner with one PO4 tetrahedra, corners with two equivalent SiO4 tetrahedra, an edgeedge with one CaO7 pentagonal bipyramid, and edges with two PO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.30–2.67 Å. In the fourth 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 2.33–2.70 Å. In the fifth 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 2.27–2.74 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three CaO7 pentagonal bipyramids and an edgeedge with one CaO7 pentagonal bipyramid. There is two shorter (1.65 Å) and two longer (1.66 Å) Si–O bond length. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share edges with two CaO7 pentagonal bipyramids. There are a spread of P–O bond distances ranging from 1.55–1.57 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three CaO7 pentagonal bipyramids and an edgeedge with one CaO7 pentagonal bipyramid. There is one shorter (1.55 Å) and three longer (1.56 Å) P–O bond length. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ 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 single-bond geometry to four Ca2+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Ca2+ and one P5+ atom. In the eleventh O2- site, O2- is bonded to three Ca2+ and one Si4+ atom to form distorted edge-sharing OCa3Si tetrahedra. In the twelfth O2- site, O2- is bonded to three Ca2+ and one P5+ atom to form distorted edge-sharing OCa3P tetrahedra.