Crystal Lattice Structures:	Creation Date:  6 Sep 2002
	Last Modified: 27 Jun 2005

The σCrFe (D8_b) Structure

You can now

• see the structure from several perspectives;
• examine the structure with an external viewer; or
• download the coordinates of the atoms in these pictures in XYZ format.
• visualize the structure (Uses the JMOL Applet)

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• The atoms in this lattice are completely disordered, that is, the Cr and Fe atoms are distributed randomly on the sites in the unit cell. This seems to be the case for all of the compounds listed below. We've chosen several of the atoms near Fe and Cr in the periodic table to color the above pictures.
• With disordered atoms, this structure is identical to βU (A_b).
• 28 June 2005: Corrected the Cartisian coordinates of the 2^nd (2a) atom.

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• Prototype: σCrFe
• Pearson Symbol: tP30
• Strukturbericht Designation: D8_b
• Space Group: P4₂/mnm (Cartesian and lattice coordinate listings available)
• Number: 136
• Reference: Villars and Calvert, Pearson's Handbook, Vol. II, p. 2639
• Other compounds with this Structure: Al₃CoNb₆, AlCrNb₃, Co₂Mo₃, Ta₃V₇, PdTa₃, IrMo₂, IrW₃, many others.
• Primitive Vectors:

  A1	=	a X
  A2	=	a Y
  A3	=	c Z

• Basis Vectors:

  B1	=	0			(M-I)	(2a)
  B2	=	½ A1 + ½ A2 + ½ A3	=	½ a X + ½ a Y + ½ c Z	(M-I)	(2a)
  B3	=	+ x2 A1 + x2 A2	=	+ a x2 X + a x2 Y	(M-II)	(4f)
  B4	=	- x2 A1 - x2 A2	=	- a x2 X - a x2 Y	(M-II)	(4f)
  B5	=	(½ + x2) A1 + (½ - x2) A2 + ½ A3	=	(½ + x2) a X + (½ - x2) a Y +½ c Z	(M-II)	(4f)
  B6	=	(½ - x2) A1 + (½ + x2) A2 + ½ A3	=	(½ - x2) a X + (½ + x2) a Y +½ c Z	(M-II)	(4f)
  B7	=	+ x3 A1 + y3 A2	=	+ x3 a X + y3 a Y	(M-III)	(8i)
  B8	=	- x3 A1 - y3 A2	=	- x3 a X - y3 a Y	(M-III)	(8i)
  B9	=	+ (½ + x3) A1 + (½ - y3) A2 + ½ A3	=	+ (½ + x3) a X + (½ - y3) a Y + ½ c Z	(M-III)	(8i)
  B10	=	+ (½ - x3) A1 + (½ + y3) A2 + ½ A3	=	+ (½ - x3) a X + (½ + y3) a Y + ½ c Z	(M-III)	(8i)
  B11	=	+ y3 A1 + x3 A2	=	+ y3 a X + x3 a Y	(M-III)	(8i)
  B12	=	- y3 A1 - x3 A2	=	- y3 a X - x3 a Y	(M-III)	(8i)
  B13	=	+ (½ + y3) A1 + (½ - x3) A2 + ½ A3	=	+ (½ + y3) a X + (½ - x3) a Y + ½ c Z	(M-III)	(8i)
  B14	=	+ (½ - y3) A1 + (½ + x3) A2 + ½ A3	=	+ (½ - y3) a X + (½ + x3) a Y + ½ c Z	(M-III)	(8i)
  B15	=	+ x4 A1 + y4 A2	=	+ x4 a X + y4 a Y	(M-IV)	(8i)
  B16	=	- x4 A1 - y4 A2	=	- x4 a X - y4 a Y	(M-IV)	(8i)
  B17	=	+ (½ + x4) A1 + (½ - y4) A2 + ½ A3	=	+ (½ + x4) a X + (½ - y4) a Y + ½ c Z	(M-IV)	(8i)
  B18	=	+ (½ - x4) A1 + (½ + y4) A2 + ½ A3	=	+ (½ - x4) a X + (½ + y4) a Y + ½ c Z	(M-IV)	(8i)
  B19	=	+ y4 A1 + x4 A2	=	+ y4 a X + x4 a Y	(M-IV)	(8i)
  B20	=	- y4 A1 - x4 A2	=	- y4 a X - x4 a Y	(M-IV)	(8i)
  B21	=	+ (½ + y4) A1 + (½ - x4) A2 + ½ A3	=	+ (½ + y4) a X + (½ - x4) a Y + ½ c Z	(M-IV)	(8i)
  B22	=	+ (½ - y4) A1 + (½ + x4) A2 + ½ A3	=	+ (½ - y4) a X + (½ + x4) a Y + ½ c Z	(M-IV)	(8i)
  B23	=	+ x5 A1 + x5 A2 + z5 A3	=	+ x5 a X + x5 a Y + z5 c Z	(M-V)	(8j)
  B24	=	- x5 A1 - x5 A2 + z5 A3	=	- x5 a X - x5 a Y + z5 c Z	(M-V)	(8j)
  B25	=	+ (½ + x5) A1 + (½ - x5) A2 + (½ + z5) A3	=	+ (½ + x5) a X + (½ - x5) a Y + (½ + z5) c Z	(M-V)	(8j)
  B26	=	+ (½ - x5) A1 + (½ + x5) A2 + (½ + z5) A3	=	+ (½ - x5) a X + (½ + x5) a Y + (½ + z5) c Z	(M-V)	(8j)
  B27	=	+ x5 A1 + x5 A2 - z5 A3	=	+ x5 a X + x5 a Y - z5 c Z	(M-V)	(8j)
  B28	=	- x5 A1 - x5 A2 - z5 A3	=	- x5 a X - x5 a Y - z5 c Z	(M-V)	(8j)
  B29	=	+ (½ + x5) A1 + (½ - x5) A2 + (½ - z5) A3	=	+ (½ + x5) a X + (½ - x5) a Y + (½ - z5) c Z	(M-V)	(8j)
  B30	=	+ (½ - x5) A1 + (½ + x5) A2 + (½ - z5) A3	=	+ (½ - x5) a X + (½ + x5) a Y + (½ - z5) c Z	(M-V)	(8j)

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Structures indexed by: Strukturbericht Symbol Pearson Symbol Space Group Prototype

This is a mirror of an old page created at the Naval Research Laboratory Center for Computational Materials Science The 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).