Crystal Lattice Structures: Creation Date: 5 Aug 1997 Last Modified: 21 Oct 2004

# The ω (C6) Phase

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• The omega phase can be either hexagonal or trigonal (shown here).
• The trigonal omega phase transforms into several high-symmetry structures under certain conditions:
c/a z Lattice
Arbitrary   0   Ideal Omega (C32)
(3/8)½   1/6   bcc (A2)
(3/2)½   1/6   simple cubic (Ah)
6½   1/6   fcc (A1)
Arbitrary   1/2   Simple Hexagonal Structure (Af)
• For more details about the omega phase and materials which form in the omega phase, see S.K. Sikka, Y.K. Vohra, and R. Chidambaram, Progress in Materials Science 27, 245-310 (1982). Most omega phase intermetallic alloys are disordered.
• Pearson's Handbook, at least, lists CdI2 as the prototype for Strukturbericht designation C6.

• Prototype: ω-CrTi, CdI2
• Pearson Symbol: hP3
• Strukturbericht Designation: C6
• Space Group: P3m1 (Cartesian and lattice coordinate listings available)
• Number: 164
• Some systems which exhibit the omega phase: Ti, Zr, Hf, ZrNb, TiNb, TiV.
• Primitive Vectors:  A1 = ½ a X - ½ 3½ aY A2 = ½ a X + ½ 3½ a Y A3 = c Z
• Basis Vectors:  B1 = 0 (Cd) (1a) B2 = 2/3 A1 + 1/3 A2 + (½ + z) A3 = ½ a X - 12-½ a Y + (½ + z) c Z (I) (2d) B3 = 1/3 A1 + 2/3 A2 + (½ - z) A3 = ½ a X + 12-½ a Y + (½ - z) c Z (I) (2d)

### See these vectors in LaTeX output format.

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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).