Materials Data on KHfMg6 by Materials Project

Abstract

KMg6Hf crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with four equivalent KMg12 cuboctahedra, corners with eight equivalent HfMg12 cuboctahedra, edges with eight equivalent MgK2Hf2Mg8 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with four equivalent MgK2Hf2Mg8 cuboctahedra, and faces with four equivalent HfMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.33–3.54 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent K, eight Mg, and two equivalent Hf atoms to form distorted MgK2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgK2Hf2Mg8 cuboctahedra, edges with four equivalent KMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with six equivalent MgK2Hf2Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.28–3.37 Å. There are one shorter (3.31 Å) and one longer (3.35 Å) Mg–Hf bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Hf atoms. There are one shorter (2.98 Å) and one longer (3.01 Å) Mg–Mg bond lengths. Both Mg–Hf bond lengths are 3.16 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Hf atoms. Both Mg–Hf bond lengths are 3.13 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Hf atoms. Both Mg–Hf bond lengths are 3.16 Å. Hf is bonded to twelve Mg atoms to form HfMg12 cuboctahedra that share corners with four equivalent HfMg12 cuboctahedra, corners with eight equivalent KMg12 cuboctahedra, edges with eight equivalent MgK2Hf2Mg8 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, faces with four equivalent KMg12 cuboctahedra, and faces with four equivalent MgK2Hf2Mg8 cuboctahedra.