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Packing Efficiency

Primitive Cubic
Coordination Number 6
52% Packing Efficiency

CCP

  Close-Packed (CCP or HCP)
Coordination Number 12
74% Packing Efficiency
Body-Centered Cubic
Coordination Number 8
68% Packing Efficiency

HCP

  • Primitive cubic is inefficient packing at 52%.

  • Body centered cubic is more efficient at 68%.

  • The most efficient packing arrangement is close packing (cubic close-packing or hexagonal close-packing) at 74%.

  • The close-packed structures have octahedral and terahedral holes that can be occupied by other atoms or ions.