Materials Data on KCaBr3 by Materials Project
KCaBr3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of K–Br bond distances ranging from 3.30–3.69 Å. Ca2+ is bonded to six Br1- atoms to form a mixture of corner and edge-sharing CaBr6 octahedra. The corner-sharing octahedral tilt angles are 42°. There are two shorter (2.90 Å) and four longer (2.94 Å) Ca–Br bond lengths. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded to two equivalent K1+ and two equivalent Ca2+ atoms to form distorted corner-sharing BrK2Ca2 tetrahedra. In the second Br1- site, Br1- is bonded in a 5-coordinate geometry to three equivalent K1+ and two equivalent Ca2+ atoms.