Void Space (or Interstitial Space)

Void Space (or Interstitial Space)

✓ The void space in the unit cell is the vacant space left unutilized in the cell.

✓ It is equal to (1 - APF). It is often expressed as percentage.

⸫ Void Space = (1-APF) × 100

Calculation of void space

Void spaces are calculated as follows for various structures.

1. Simple Cubic (SC) structure

A.P.F for SC lattice = 0.52

⸫ Void space = (1 - APF) × 100 

                       = (1-0.52) × 100 = 48%

2. Body Centred Cubic (BCC) structure

A.P.F for BCC lattice = 0.68

⸫ Void space = (1 - APF) × 100

                      = (1 - 0.68) × 100 = 32%

3. Face Centred Cubic (FCC) structure

A.P.F for FCC lattice = 0.74

⸫ Void space = (1 - APF) × 100

                      = (1 - 0.74) × 100 = 26%

4. Hexagonal Close Packed (HCP) structure

A.F.F for HCP lattice = 0.74

⸫ Void space = (1 - APF) × 100

                      = (1 - 0.74) × 100 = 26%