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DOE OSTI2020

Materials Data on FeSiGe by Materials Project

FeSiGe is Magnesium tetraboride-derived structured and crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded in a 8-coordinate geometry to four equivalent Ge2+ and four equivalent Si4- atoms. There are two shorter (2.40 Å) and two longer (2.43 Å) Fe–Ge bond lengths. There are two shorter (2.38 Å) and two longer (2.46 Å) Fe–Si bond lengths. In the second Fe2+ site, Fe2+ is bonded in a 8-coordinate geometry to four equivalent Ge2+ and four equivalent Si4- atoms. There are two shorter (2.41 Å) and two longer (2.49 Å) Fe–Ge bond lengths. There are two shorter (2.37 Å) and two longer (2.50 Å) Fe–Si bond lengths. Ge2+ is bonded in a 7-coordinate geometry to four Fe2+ and three equivalent Si4- atoms. There are a spread of Ge–Si bond distances ranging from 2.54–2.68 Å. Si4- is bonded in a 9-coordinate geometry to four Fe2+, three equivalent Ge2+, and two equivalent Si4- atoms. There are one shorter (2.53 Å) and one longer (2.57 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on FeSiGe by Materials Project

FeSiGe is Magnesium tetraboride-derived structured and crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded in a 8-coordinate geometry to four equivalent Ge2+ and four equivalent Si4- atoms. There are two shorter (2.41 Å) and two longer (2.45 Å) Fe–Ge bond lengths. There are two shorter (2.36 Å) and two longer (2.44 Å) Fe–Si bond lengths. In the second Fe2+ site, Fe2+ is bonded in a 8-coordinate geometry to four equivalent Ge2+ and four equivalent Si4- atoms. There are two shorter (2.39 Å) and two longer (2.47 Å) Fe–Ge bond lengths. There are two shorter (2.34 Å) and two longer (2.55 Å) Fe–Si bond lengths. Ge2+ is bonded in a 7-coordinate geometry to four Fe2+ and three equivalent Si4- atoms. There are a spread of Ge–Si bond distances ranging from 2.57–2.63 Å. Si4- is bonded in a 9-coordinate geometry to four Fe2+, three equivalent Ge2+, and two equivalent Si4- atoms. There are one shorter (2.61 Å) and one longer (2.62 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗

NASA NTRS1987

Rare-earth substitution in (BiYCa)3(FeSiGe)5O12 bubble films

The substitution of Y by Sm, Tb, Gd, and Ho in (BiYCa)3 FeSiGe)5O12 bubble garnet is shown to have large effects on the growth-induced anisotropy (GIA). The presently accepted film composition intended for 6-or 8-micron-period bubble memory devices demands partial substitution of Y by Gd and Ho. However, comparing films grown under the same growth conditions, it is observed that YGdHoBilG films posess less (GIA) than their Gd, Ho-free counterparts. Thus, to satisfy (GIA) requirements, the supercooling during growth must be increased by 20 K to 80 K with undesirable effects on defect densities. A new film composition containing Sm, Tb, and Gd has been formulated to satisfy all known material property specifications for 6- or 8-micron-period memory devices. It can be grown with only 45-50 K supercooling.

Luther, L. C.↗