DOI: 10.17188/1263170
title: Materials Data on Ca4P2O9 by Materials Project

description: Ca4(PO4)2O crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are eight inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.21–2.76 Å. In the second 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 2.22–2.87 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 2.19–2.66 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 2.24–2.89 Å. In the fifth Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted CaO7 pentagonal bipyramids that share corners with four PO4 tetrahedra and an edgeedge with one PO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.30–2.61 Å. In the sixth 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 2.15–2.83 Å. In the seventh 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 2.26–2.61 Å. In the eighth 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 2.22–2.82 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent CaO7 pentagonal bipyramids. 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 a cornercorner with one CaO7 pentagonal bipyramid. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share an edgeedge with one CaO7 pentagonal bipyramid. There is two shorter (1.54 Å) and two longer (1.56 Å) P–O bond length. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CaO7 pentagonal bipyramid. There are a spread of P–O bond distances ranging from 1.55–1.57 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one P5+ 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 4-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 1-coordinate geometry to three Ca2+ and one P5+ atom. In the sixth O2- site, O2- is bonded to four Ca2+ atoms to form corner-sharing OCa4 tetrahedra. In the seventh O2- site, O2- is bonded in a tetrahedral geometry to four Ca2+ atoms. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one P5+ 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 4-coordinate geometry to three Ca2+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one P5+ atom. In the eighteenth O2- site, O2- is bonded to three Ca2+ and one P5+ atom to form distorted corner-sharing OCa3P tetrahedra.