Hexagonal close-packed Mg

Unit cell

Lattice constants

a = 3.210 Å, b = 3.210 Å, c = 5.210 Å; α = 90°, β = 90°, γ = 120°

Cell volume

46.5 ų

Atoms in the cell

2 (Mg 2)

Formula units Z

2

Calculated density

1.74 g cm⁻³

Shortest contact

3.197 Å

Packing efficiency

73.6 %

Coordination

Mg

CN 12 at 3.20 Å (12 Mg)

About the structure

• Hexagonal close packing: layers stack ABAB along c.
• Ideal c/a = √(8/3) = 1.633; Mg has 1.623.
• Same packing efficiency (≈74%) and coordination number (12) as ccp; the difference is the third layer.
• Mg, Zn, Cd, Ti, Co, Zr adopt this structure.

Atom positions (fractional, one cell)

Z, coordination numbers, distances, density and packing on this page are computed from these coordinates.