Crystal Lattice Structures:	Creation Date: 26 Apr 1988
	Last Modified: 17 Feb 2007

The αLa (A3') 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 crystal is close-packed, with stacking ABACABAC..., as opposed to ABAB... for the hcp (A3) lattice and ABCABC... for the fcc (A1) lattice. The (2a) crystallographic sites (the A's) form a simple hexagonal lattice. The (2c) sites (the B's and C's) form an hcp structure.

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• Prototype: alpha La
• Pearson Symbol: hP4
• Strukturbericht Designation: A3'
• Space Group: P6₃/mmc (Cartesian and lattice coordinate listings available)
• Number: 194
• Reference: Donohue, Structures of the Elements, p 87.
• Other elements with this structure: Pr, Nd, Pm, Ce, Am, Cm, Bk, Cf
• Primitive Vectors:

  A1	=	½ a X - ½ 3½ a Y
  A2	=	½ a X + ½ 3½ a Y
  A3	=	c Z

• Basis Vectors:

  B1	=		0		(2a)
  B2	=	½ A3	=	½ c Z	(2a)
  B3	=	1/3 A1 + 2/3 A2 + ¼ A3	=	½ a X + ½ 3-½ a Y + ¼ c Z	(2c)
  B4	=	2/3 A1 + 1/3 A2 + ¾ A3	=	½ a X - ½ 3-½ a Y + ¾ c Z	(2c)

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Structures indexed by: Strukturbericht Symbol Pearson Symbol Space Group Prototype

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