Materials Data on Mg4Si7 by Materials Project

Abstract

Mg4Si7 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Mg sites. In the first Mg site, Mg is bonded in a 11-coordinate geometry to eleven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.73–3.00 Å. In the second Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.61–3.03 Å. In the third Mg site, Mg is bonded in a 11-coordinate geometry to two Mg and nine Si atoms. There are one shorter (3.05 Å) and one longer (3.10 Å) Mg–Mg bond lengths. There are a spread of Mg–Si bond distances ranging from 2.75–3.08 Å. In the fourth Mg site, Mg is bonded in a 6-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.81–3.11 Å. In the fifth Mg site, Mg is bonded to five Si atoms to form distorted MgSi5 trigonal bipyramids that share corners with four equivalent SiMg4Si4 hexagonal bipyramids, corners with two equivalent SiMg3Si4 hexagonal pyramids, and corners with two equivalent MgSi5 trigonal bipyramids. There are a spread of Mg–Si bond distances ranging from 2.78–2.88 Å. In the sixth Mg site, Mg is bonded in a 1-coordinate geometry to one Mg and nine Si atoms. There are a spread of Mg–Si bond distances ranging from 2.69–3.03 Å. In the seventh Mg site, Mg is bonded in a 12-coordinate geometry to one Mg and seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.65–3.15 Å. In the eighth Mg site, Mg is bonded in a 2-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.85–3.21 Å. There are fourteen inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to three Mg and five Si atoms. There are a spread of Si–Si bond distances ranging from 2.41–2.80 Å. In the second Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are one shorter (2.39 Å) and two longer (2.58 Å) Si–Si bond lengths. In the third Si site, Si is bonded in a 7-coordinate geometry to three Mg and four Si atoms. There are one shorter (2.49 Å) and one longer (2.54 Å) Si–Si bond lengths. In the fourth Si site, Si is bonded to three Mg and four Si atoms to form distorted SiMg3Si4 hexagonal pyramids that share corners with two equivalent SiMg4Si4 hexagonal bipyramids, corners with two equivalent MgSi5 trigonal bipyramids, edges with two equivalent SiMg3Si4 hexagonal pyramids, and a faceface with one SiMg4Si4 hexagonal bipyramid. The Si–Si bond length is 2.45 Å. In the fifth Si site, Si is bonded in a 7-coordinate geometry to seven Mg and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.37–2.83 Å. In the sixth Si site, Si is bonded in a 1-coordinate geometry to five Mg and two Si atoms. The Si–Si bond length is 2.42 Å. In the seventh Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. There are one shorter (2.42 Å) and one longer (2.56 Å) Si–Si bond lengths. In the eighth Si site, Si is bonded to four Mg and four Si atoms to form distorted SiMg4Si4 hexagonal bipyramids that share corners with two equivalent SiMg3Si4 hexagonal pyramids, corners with four equivalent MgSi5 trigonal bipyramids, edges with two equivalent SiMg4Si4 hexagonal bipyramids, and a faceface with one SiMg3Si4 hexagonal pyramid. There are one shorter (2.49 Å) and two longer (2.54 Å) Si–Si bond lengths. In the ninth Si site, Si is bonded in a 7-coordinate geometry to six Mg and two Si atoms. The Si–Si bond length is 2.44 Å. In the tenth Si site, Si is bonded in a 8-coordinate geometry to three Mg and five Si atoms. There are one shorter (2.56 Å) and two longer (2.66 Å) Si–Si bond lengths. In the eleventh Si site, Si is bonded in a 9-coordinate geometry to five Mg and four Si atoms. There are one shorter (2.74 Å) and one longer (2.76 Å) Si–Si bond lengths. In the twelfth Si site, Si is bonded in a 7-coordinate geometry to five Mg and two Si atoms. In the thirteenth Si site, Si is bonded in a 8-coordinate geometry to four Mg and four Si atoms. In the fourteenth Si site, Si is bonded in a 1-coordinate geometry to five Mg and five Si atoms.