Hcp

HCP Structure

The sample element is taken as Magnesium (Mg)

Figure 1. Basic hexagonal closed packed (hcp) crystal structure.

• Primitive Vectors:

A1 = ½ a X - ½ 31/2 a Y
A2 = ½ a X + ½ 31/2 a Y
A3 = c Z

• Basis Vector:

B1 = 1/3 A1 + 2/3 A2 + ¼ A3 (Mg) (2c)
B2 = 2/3 A1 + 1/3 A2 + ¾ A3 (Mg) (2c)

However in orthogonal unitcell:

A1 = a X
A2 = b Y
A3 = c Z

where b = Sqrt(3)a

And the Basis vectors:

B1 = 1/4 a 1/3 b 1/4 c
B2 = 3/4 a 5/6 b 1/4 c
B2 = 1/4 a 0 b 3/4 c
B2 = 3/4 a 1/2 b 3/4 c