## What is the lattice parameter of hcp?

The optimized lattice parameters of the hcp structure are ahcp = 2.722 Å and chcp = 4.386 Å, giving the unit cell volume of 28.46 Å3, or 14.23 Å3 per atom. The optimized lattice parameters of the fcc structure are afcc = 3.829 Å, giving the unit cell volume of 56.70 Å3, or 14.17 Å3 per atom.

### How do you convert FCC to HCP?

Two layers of fcc structure will be converted into hcp structure when one a /6 〈 11 ̄ ] Shockley partial dislocation sweeps through a {111} ␥ plane; then another two layers of hcp structure will be obtained when another a /6 〈 11 ̄ ] Shockley partial dislocation glides on every other {111} ␥ plane.

#### What is the coordination number for fcc lattice?

12

Coordination number – the number of nearest neighbor atoms or ions surrounding an atom or ion. For FCC and HCP systems, the coordination number is 12.

**What is the coordination number in hcp lattice?**

The hexagonal closest packed (hcp) has a coordination number of 12 and contains 6 atoms per unit cell.

**How do you find the lattice parameter for FCC?**

If the space lattice is FCC, the lattice constant is given by the formula [4 x r / (2)1/2] and if the space lattice is BCC, then the lattice constant is given by the formula a = [4 x r / (3)1/2].

## How do you find the lattice constant for hcp?

HCP has 6 atoms per unit cell, lattice constant a = 2r and c = (4√6r)/3 (or c/a ratio = 1.633), coordination number CN = 12, and Atomic Packing Factor APF = 74%.

### Is HCP and FCC same?

You might think a face-centered cubic (FCC) crystal wouldn’t have much in common with a hexagonal close-packed (HCP) crystal, but by certain definitions, they are actually the same thing! FCC and HCP are both close-packed with a 74% atomic packing factor, 12 nearest neighbors, and the same interstitial sites.

#### What is the difference between FCC and HCP arrangements?

The key difference between FCC and HCP is that FCC structure cycles among three layers whereas HCP structure cycles among two layers. FCC is a face-centred cubic close-packed structure while HCP is a hexagonal close-packed structure.

**Are HCP and FCC same?**

**How the packing sequence of FCC is different from HCP?**

FCC is a face-centred cubic close packing structure of lattices while HCP is hexagonal close packing structure of lattices. The key difference between FCC and HCP is that FCC structure cycles among three layers whereas HCP structure cycles among two layers.