Materials Data on KCaAsO12 by Materials Project
KCaAsO12 crystallizes in the orthorhombic Amm2 space group. The structure is two-dimensional and consists of two KCaAsO12 sheets oriented in the (0, 1, 0) direction. K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.80–3.29 Å. Ca is bonded in a 6-coordinate geometry to six O atoms. There are two shorter (2.11 Å) and four longer (2.58 Å) Ca–O bond lengths. As is bonded in a tetrahedral geometry to four O atoms. There is two shorter (1.71 Å) and two longer (1.73 Å) As–O bond length. There are five inequivalent O sites. In the first O site, O is bonded in a linear geometry to one Ca and one As atom. In the second O site, O is bonded in a single-bond geometry to one As atom. In the third O site, O is bonded in a bent 120 degrees geometry to one K and one O atom. The O–O bond length is 1.23 Å. In the fourth O site, O is bonded in a distorted L-shaped geometry to one K and one O atom. The O–O bond length is 1.24 Å. In the fifth O site, O is bonded in a distorted T-shaped geometry to one K, one Ca, and one O atom. The O–O bond length is 1.28 Å.