The omega (C6) Phase

Last modified 11 April 2001

The omega phase can be either hexagonal or trigonal (shown here).

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• 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.

The trigonal omega phase transforms into several high-symmetry structures under certain conditions:

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: omega-CrTi, CdI₂
• Pearson Symbol: hP3
• Strukturbericht Designation: C6
• Space Group: P(-3)m1 (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 3^1/2 a Y
  • A₂ = ½ a X + ½ 3^1/2 a Y
  • A₃ = c Z
• Basis Vector:
  • B₁= 0   (1a)
  • B₂ = 2/3 A₁ + 1/3 A₂ + (½ + z) A₃ = ½ a X - ½ 3^-1/2 a Y + (½ + z) c Z   (2d)
  • B₃ = 1/3 A₁ + 2/3 A₂ + (½ - z) A₃ = ½ a X + ½ 3^-1/2 a Y + (½ - z) c Z   (2d)

See these vectors in a better notation.

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Structures indexed by:

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