DOE OSTI2020
CaZn2(PO4)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.60 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Zn–O bond distances ranging from 1.97–2.60 Å. In the second Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with four PO4 tetrahedra. There are a spread of Zn–O bond distances ranging from 1.94–2.04 Å. There are two 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 ZnO4 tetrahedra. 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 equivalent ZnO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.52–1.58 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+, one Zn2+, and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Zn2+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Zn2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Zn2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Zn2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Zn2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Zn2+, and one P5+ atom.