Crystal Lattice Structures: Creation Date: 13 Sep 2002 Last Modified: 21 Oct 2004

# The Hypothetical cF128 Ferrite Structure

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• Ferrite is steel with a bcc structure. This structure represents one possible ordering which might be found in an Fe-Ni-Cr steel. Note that it is not meant to represent a real steel.
• If we use the special values  x1 = 1/8 x2 = 1/4 x3 = 38
and replace the Ni atoms by Cr, then this structure reverts to CsCl (B2) with aB2 = ¼ a. If we replace both the Ni and Cr atoms by Fe, then the structure becomes bcc, again with abcc = ¼ a.
• 18 July 2008: Corrected the Wyckoff positions of the Fe-II atoms.

• Prototype: Cr9Fe16Ni7 (hypothetical)
• Pearson Symbol: cF128
• Space Group: Fm3m (Cartesian and lattice coordinate listings available)
• Number: 225
• Primitive Vectors:  A1 = + ½ a Y + ½ a Z A2 = + ½ a X + ½ a Z A3 = + ½ a X + ½ a Y
• Basis Vectors:  B1 = 0 (Cr-I) (4a) B2 = + x1 A1 + x1 A2 + x1 A3 = + x1 a X + x1 a Y + x1 a Z (Fe-I) (32f) B3 = + 3 x1 A1 - x1 A2 - x1 A3 = - x1 a X + x1 a Y + x1 a Z (Fe-I) (32f) B4 = - x1 A1 + 3 x1 A2 - x1 A3 = + x1 a X - x1 a Y + x1 a Z (Fe-I) (32f) B5 = - x1 A1 - x1 A2 + 3 x1 A3 = + x1 a X + x1 a Y - x1 a Z (Fe-I) (32f) B6 = - x1 A1 - x1 A2 - x1 A3 = - x1 a X - x1 a Y - x1 a Z (Fe-I) (32f) B7 = - 3 x1 A1 + x1 A2 + x1 A3 = + x1 a X - x1 a Y - x1 a Z (Fe-I) (32f) B8 = + x1 A1 - 3 x1 A2 + x1 A3 = - x1 a X + x1 a Y - x1 a Z (Fe-I) (32f) B9 = + x1 A1 + x1 A2 - 3 x1 A3 = - x1 a X - x1 a Y + x1 a Z (Fe-I) (32f) B10 = - x2 A1 + x2 A2 + x2 A3 = + x2 a X (Ni-I) (24e) B11 = + x2 A1 - x2 A2 + x2 A3 = + x2 a Y (Ni-I) (24e) B12 = + x2 A1 + x2 A2 - x2 A3 = + x2 a Z (Ni-I) (24e) B13 = + x2 A1 - x2 A2 - x2 A3 = - x2 a X (Ni-I) (24e) B14 = - x2 A1 + x2 A2 - x2 A3 = - x2 a Y (Ni-I) (24e) B15 = - x2 A1 - x2 A2 + x2 A3 = - x2 a Z (Ni-I) (24e) B16 = + ½ A1 = + ¼ a Y + ¼ a Z (Cr-II) (24d) B17 = + ½ A2 = + ¼ a X + ¼ a Z (Cr-II) (24d) B18 = + ½ A3 = + ¼ a X + ¼ a Y (Cr-II) (24d) B19 = - ½ A2 + ½ A3 = + ¼ a Y - ¼ a Z (Cr-II) (24d) B20 = - ½ A1 + ½ A3 = + ¼ a X - ¼ a Z (Cr-II) (24d) B21 = - ½ A1 + ½ A2 = + ¼ a X - ¼ a Y (Cr-II) (24d) B22 = + (x3 - 1) A1 + x3 A2 + x3 A3 = + x3 a X + (x3 - ½) a Y + (x3 - ½) a Z (Fe-II) (32f) B23 = + (3 x3 - 1) A1 - x3 A2 - x3 A3 = - x3 a X + (x3 - ½) a Y + (x3 - ½) a Z (Fe-II) (32f) B24 = - x3 A1 + (3 x3 - 1) A2 - x3 A3 = + (x3 - ½) a X - x3 a Y + (x3 - ½) a Z (Fe-II) (32f) B25 = - x3 A1 - x3 A2 + (3 x3 - 1) A3 = + (x3 - ½) a X + (x3 - ½) a Y - x3 a Z (Fe-II) (32f) B26 = - (x3 - 1) A1 - x3 A2 - x3 A3 = - x3 a X - (x3 - ½) a Y - (x3 - ½) a Z (Fe-II) (32f) B27 = - (3 x3 - 1) A1 + x3 A2 + x3 A3 = + x3 a X - (x3 - ½) a Y - (x3 - ½) a Z (Fe-II) (32f) B28 = + x3 A1 - (3 x3 - 1) A2 + x3 A3 = - (x3 - ½) a X + x3 a Y - (x3 - ½) a Z (Fe-II) (32f) B29 = + x3 A1 + x3 A2 - (3 x3 - 1) A3 = - (x3 - ½) a X - (x3 - ½) a Y + x3 a Z (Fe-II) (32f) B30 = + ¼ A1 + ¼ A2 + ¼ A3 = + ¼ a X + ¼ a Y + ¼ a Z (Cr-III) (8c) B31 = - ¼ A1 - ¼ A2 - ¼ A3 = - ¼ a X - ¼ a Y - ¼ a Z (Cr-III) (8c) B32 = + ½ A1 + ½ A2 + ½ A3 = + ½ a X + ½ a Y + ½ a Z (Ni-II) (4b)

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 Structures indexed by: This is a mirror of an old page created at theNaval Research LaboratoryCenter for Computational Materials ScienceThe maintained successor is hosted at http://www.aflowlib.org/CrystalDatabase/ and published as M. Mehl et al., Comput. Mater. Sci. 136 (Supp.), S1-S828 (2017).