Crystal Lattice Structures:	Creation Date: 18 Sep 2001
	Last Modified: 21 Oct 2004

The AlCCr₂ 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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• Note that all of the atoms sit on close packed <0001> planes. The stacking sequence may be written
  
  

  Atom	Cr	C	Cr	Al	Cr	C	Cr	Al
  Position	B	A	C	B	C	A	B	C

  
  
  
• Thus the C and Cr atoms are always in an fcc-like local environment, while the Al atoms are in an hcp-like local environment.

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• Prototype: AlCCr₂
• Pearson Symbol: hP8
• Space Group: P6₃/mmc (Cartesian and lattice coordinate listings available)
• Number: 194
• Other compounds with this structure: Cr₂GaN, CeGeLi₂, many others
  MAX phases: AlCNb₂, AlCTi₂, AlNTi₂, AsCNb₂, CCrGe₂, AlCV₂, more.
• Primitive Vectors:

  A1	=	½ a X - ½ 31/2 a Y
  A2	=	½ a X + ½ 31/2 a Y
  A3	=	c Z

• Basis Vectors:

  B1	=		0		(C)	(2a)
  B2	=	½ A3	=	½ c  Z	(C)	(2a)
  B3	=	2/3 a A1  + 1/3 a A2  + ¼ A3	=	½ a X - ½ 3-1/2 a Y + ¼ c  Z	(Al)	(2d)
  B4	=	1/3 a A1  + 2/3 a A2  + ¾ A3	=	½ a X + ½ 3-1/2 a Y + ¾ c  Z	(Al)	(2d)
  B5	=	2/3 a A1  + 1/3 a A2  - z A3	=	½ a X + ½ 3-1/2 a Y - z   c  Z	(Cr)	(4f)
  B6	=	1/3 a A1  + 2/3 a A2  + z A3	=	½ a X - ½ 3-1/2 a Y + z   c  Z	(Cr)	(4f)
  B7	=	1/3 a A1  + 2/3 a A2  + (½ - z) A3	=	½ a X + ½ 3-1/2 a Y + (½ - z) c  Z	(Cr)	(4f)
  B8	=	2/3 a A1  + 1/3 a A2  + (½ + z) A3	=	½ a X - ½ 3-1/2 a Y + (½ + z) c  Z	(Cr)	(4f)

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Go back to the hexagonal close packed Crystal Structure page.

Go back to Crystal Lattice Structure page.

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).