Materials Data on K2Er2(PO4)3 by Materials Project
K2Er2(PO4)3 crystallizes in the cubic P2_13 space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 3-coordinate geometry to three equivalent O atoms. All K–O bond lengths are 3.07 Å. In the second K site, K is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of K–O bond distances ranging from 3.09–3.33 Å. There are two inequivalent Er sites. In the first Er site, Er is bonded to six O atoms to form ErO6 octahedra that share corners with six equivalent PO4 tetrahedra. There are three shorter (2.23 Å) and three longer (2.24 Å) Er–O bond lengths. In the second Er site, Er is bonded to six O atoms to form ErO6 octahedra that share corners with six equivalent PO4 tetrahedra. There are three shorter (2.20 Å) and three longer (2.23 Å) Er–O bond lengths. P is bonded to four O atoms to form PO4 tetrahedra that share corners with four ErO6 octahedra. The corner-sharing octahedra tilt angles range from 11–45°. There is one shorter (1.54 Å) and three longer (1.55 Å) P–O bond length. There are four inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to one K, one Er, and one P atom. In the second O site, O is bonded in a distorted linear geometry to one K, one Er, and one P atom. In the third O site, O is bonded in a 3-coordinate geometry to one K, one Er, and one P atom. In the fourth O site, O is bonded in a distorted bent 150 degrees geometry to one K, one Er, and one P atom.