Materials Data on BaHfMg6 by Materials Project

Abstract

BaMg6Hf crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Ba is bonded to ten Mg and two equivalent Hf atoms to form BaHf2Mg10 cuboctahedra that share corners with four equivalent MgBa2Mg10 cuboctahedra, corners with six equivalent BaHf2Mg10 cuboctahedra, edges with two equivalent MgBa2Mg10 cuboctahedra, edges with four equivalent HfBa2Mg10 cuboctahedra, faces with two equivalent BaHf2Mg10 cuboctahedra, faces with two equivalent HfBa2Mg10 cuboctahedra, and faces with eight MgBa2Mg10 cuboctahedra. There are a spread of Ba–Mg bond distances ranging from 3.30–3.44 Å. Both Ba–Hf bond lengths are 3.40 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Ba, seven Mg, and two equivalent Hf atoms. There are a spread of Mg–Mg bond distances ranging from 3.16–3.41 Å. Both Mg–Hf bond lengths are 3.22 Å. In the second Mg site, Mg is bonded to two equivalent Ba and ten Mg atoms to form distorted MgBa2Mg10 cuboctahedra that share corners with four equivalent BaHf2Mg10 cuboctahedra, corners with six equivalent MgBa2Mg10 cuboctahedra, edges with two equivalent BaHf2Mg10 cuboctahedra, edges with four equivalent MgHf2Mg10 cuboctahedra, faces with two equivalent BaHf2Mg10 cuboctahedra, faces with four MgBa2Mg10 cuboctahedra, and faces with six equivalent HfBa2Mg10 cuboctahedra. There are four shorter (3.29 Å) and two longer (3.34 Å) Mg–Mg bond lengths. In the third Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Ba, eight Mg, and two equivalent Hf atoms. There are a spread of Mg–Mg bond distances ranging from 3.20–3.53 Å. There are one shorter (3.15 Å) and one longer (3.58 Å) Mg–Hf bond lengths. In the fourth Mg site, Mg is bonded to ten Mg and two equivalent Hf atoms to form MgHf2Mg10 cuboctahedra that share corners with four equivalent HfBa2Mg10 cuboctahedra, corners with six equivalent MgHf2Mg10 cuboctahedra, edges with two equivalent HfBa2Mg10 cuboctahedra, edges with four equivalent MgBa2Mg10 cuboctahedra, faces with two equivalent HfBa2Mg10 cuboctahedra, faces with four MgBa2Mg10 cuboctahedra, and faces with six equivalent BaHf2Mg10 cuboctahedra. Both Mg–Hf bond lengths are 3.37 Å. Hf is bonded to two equivalent Ba and ten Mg atoms to form distorted HfBa2Mg10 cuboctahedra that share corners with four equivalent MgHf2Mg10 cuboctahedra, corners with six equivalent HfBa2Mg10 cuboctahedra, edges with two equivalent MgHf2Mg10 cuboctahedra, edges with four equivalent BaHf2Mg10 cuboctahedra, faces with two equivalent BaHf2Mg10 cuboctahedra, faces with two equivalent HfBa2Mg10 cuboctahedra, and faces with eight MgBa2Mg10 cuboctahedra.