Materials Data on Ca3As2O19 by Materials Project
(Ca3(AsO8)2)2(O2)3 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of two trioxidane molecules and one Ca3(AsO8)2 sheet oriented in the (0, 0, 1) direction. In the Ca3(AsO8)2 sheet, there are three inequivalent Ca sites. In the first Ca site, Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.24–3.00 Å. In the second Ca site, Ca is bonded to seven O atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent AsO4 tetrahedra and a cornercorner with one AsO4 trigonal pyramid. There are a spread of Ca–O bond distances ranging from 2.30–2.84 Å. In the third Ca site, Ca is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.25–2.57 Å. There are two inequivalent As sites. In the first As site, As is bonded to four O atoms to form distorted AsO4 trigonal pyramids that share a cornercorner with one CaO7 pentagonal bipyramid. There are a spread of As–O bond distances ranging from 1.65–2.07 Å. In the second As site, As is bonded to four O atoms to form AsO4 tetrahedra that share corners with two equivalent CaO7 pentagonal bipyramids. There are a spread of As–O bond distances ranging from 1.70–1.75 Å. There are sixteen inequivalent O sites. In the first O site, O is bonded in a trigonal planar geometry to one Ca, one As, and one O atom. The O–O bond length is 1.31 Å. In the second O site, O is bonded in a 3-coordinate geometry to one Ca, one As, and one O atom. The O–O bond length is 1.42 Å. In the third O site, O is bonded in a single-bond geometry to one As atom. In the fourth O site, O is bonded in a trigonal non-coplanar geometry to two Ca and one As atom. In the fifth O site, O is bonded in a 4-coordinate geometry to three Ca and one As atom. In the sixth O site, O is bonded in a distorted trigonal planar geometry to two Ca and one As atom. In the seventh O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one As atom. In the eighth O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one O atom. The O–O bond length is 1.23 Å. In the ninth O site, O is bonded in a distorted T-shaped geometry to two Ca and one O atom. The O–O bond length is 1.33 Å. In the tenth O site, O is bonded in a distorted T-shaped geometry to two Ca and one O atom. The O–O bond length is 1.34 Å. In the eleventh O site, O is bonded in a trigonal non-coplanar geometry to two Ca and one O atom. In the twelfth O site, O is bonded in a bent 120 degrees geometry to two Ca atoms. In the thirteenth O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and one O atom. In the fourteenth O site, O is bonded in a water-like geometry to one Ca and one As atom. In the fifteenth O site, O is bonded in a single-bond geometry to one O atom. In the sixteenth O site, O is bonded in a bent 120 degrees geometry to two O atoms.