The Moissanite-6H CSi Crystal Structure

Last modified 2 July 2001

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This is an alternate stacking (ABCACB) for tetrahedral structures. Compare this to Zincblende (ABCABC) and Wurtzite (ABABAB). The 6H refers to the fact that there are 6 CSi dimers in a hexagonal unit cell. Zincblende is denoted 3C, and Wurtzite is 2H.

• Prototype: CSi
• Pearson Symbol: hP12
• Space Group: P6₃mc (Cartesian and lattice coordinate listings available)
• Number: 186
• 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 Vectors:

  B1	=		0		(Si-I)	(2a)
  B2	=	½ A3	=	½ c Z	(Si-I)	(2a)
  B3	=	z1 A3	=	z1 c Z	(C-I)	(2a)
  B4	=	(½ + z1) A3	=	(½ + z1) c Z	(C-I)	(2a)
  B5	=	1/3 A1 + 2/3 A2 + z2 A3	=	½ a X + a/(2 3½) Y + z2 c Z	(Si-II)	(2b)
  B6	=	2/3 A1 + 1/3 A2 + (½ + z2) A3	=	½ a X - a/(2 3½) Y + (½ + z2) c Z	(Si-II)	(2b)
  B7	=	1/3 A1 + 2/3 A2 + z3 A3	=	½ a X + a/(2 3½) Y + z3 c Z	(C-II)	(2b)
  B8	=	2/3 A1 + 1/3 A2 + (½ + z3) A3	=	½ a X - a/(2 3½) Y + (½ + z3) c Z	(C-II)	(2b)
  B9	=	1/3 A1 + 2/3 A2 + z4 A3	=	½ a X + a/(2 3½) Y + z4 c Z	(Si-III)	(2b)
  B10	=	2/3 A1 + 1/3 A2 + (½ + z4) A3	=	½ a X - a/(2 3½) Y + (½ + z4) c Z	(Si-III)	(2b)
  B11	=	1/3 A1 + 2/3 A2 + z5 A3	=	½ a X + a/(2 3½) Y + z5 c Z	(C-III)	(2b)
  B12	=	2/3 A1 + 1/3 A2 + (½ + z5) A3	=	½ a X - a/(2 3½) Y + (½ + z5) c Z	(C-III)	(2b)

See these vectors in a better notation.

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