Crystal Lattice Structures:	Creation Date: 12 Apr 2001
	Last Modified:  6 Jul 2005

The Ideal β-Cristobalite (C9) 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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• This is the idealized version of the high-temperature phase of α-Cristobalite. Pearson's Handbook says that the the Si atoms partially occupy the (96g) positions in the Fd3m space group.
• The silicon atoms occupy the positions they take in the diamond (A4) structure, while the oxygen atoms form bridges between them.
• We previously messed up the basis vectors for the oxygen atoms by mistakenly labeling the Cartesian coordinates as lattice coordinates. The atomic position file was always correct.
• The positions of the atoms are taken from Wyckoff, but the lattice constant is taken from Pearson's Handbook.
• 6 July 2006: Corrected labeling of the last basis vector.

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• Prototype: SiO₂ (ideal β-Cristobalite)
• Pearson Symbol: cF24
• Strukturbericht Designation: C9
• Space Group: Fd3m (Cartesian and lattice coordinate listings available)
• Number: 227
• Reference: Wyckoff, Vol. I, p. 318-19.
• Other compounds with this structure: BeF₂
• 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	=	+ 1/8 A1 + 1/8 A2 + 1/8 A3	=	+ 1/8 a X + 1/8 a Y + 1/8 a Z	(8a)	(Si)
  B2	=	- 1/8 A1 - 1/8 A2 - 1/8 A3	=	- 1/8 a X - 1/8 a Y - 1/8 a Z	(8a)	(Si)
  B3	=	0			(16c)	(O)
  B4	=	½ A1	=	¼ a Y + ¼ a Z	(16c)	(O)
  B5	=	½ A2	=	¼ a X + ¼ a Z	(16c)	(O)
  B6	=	½ A3	=	¼ a X + ¼ a Y	(16c)	(O)

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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).