## What is the packing fraction in 2d HCP?

A. π3√2.

**What is hexagonal close packing and cubic?**

Hexagonal close packing (HCP) Cubic Close Packing. HCP is a meeting of spheres during a lattice. Cubic close packing (CCP) is an arrangement of spheres in a lattice. There are two layers of spheres placed one on the others, forming tetrahedral and octahedral holes.

### Is hexagonal close packing and cubic close packing same?

The hexagonal and cubic close packing arrangement are used to describe the arrangement of spheres and holes in lattices. The difference between hexagonal close packing and cubic close packing is that a unit cell of hexagonal close packing has 6 spheres whereas a unit cell of cubic close packing has 4 spheres.

**What is the structure of HCP?**

There are three layers in the hexagonal packing structure. There are six atoms each arranged in a shape of a hexagon in the top and the bottom layer and a seventh atom in the middle of the hexagon is present. There are three layers in the middle layer between the atoms of the top and bottom layers.

## What is the volume of HCP unit cell?

Volume =63 ×r2× 4r=242 r3.

**How do you calculate the HCP atomic packing factor?**

Calculating the atomic packing factor for a crystal is simple: for some repeating volume, calculate the volume of the atoms inside and divide by the total volume. Usually, this “repeating volume” is just the volume of the unit cell. The unit cell is defined as the simplest repeating unit in a crystal.

### What is CCP structure?

A CCP arrangement consists of three repeating layers (ABCABC…) of hexagonally arranged atoms. Atoms in a CCP structure have a coordination number of 12 because they contact six atoms in their layer, plus three atoms in the layer above and three atoms in the layer below.

**How many atoms are in HCP?**

6 atoms

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

## How will you distinguish between hcp and CCP?

There are few types of close packed crystal structures such as HCP (Hexagonal closest packed) and CCP (Cubic closest packed). The key difference between HCP and CCP is that the repeating structure of HCP has 2 layers of spheres whereas the repeating structure of CCP has 3 layers of spheres.

**What is the coordination number of hcp and CCP?**

12

-ccp stands for cubic close packed and the coordination number is 12. -Similarly, hcp stands for hexagonal close packed cell and the coordination number is 12.

### How many close packed planes does HCP have?

HCP is a closed-packed structure and therefore, by the same argument as that used for FCC, it has a coordination number of 12 (provided the c/a ratio shown in fig.

**Which is the example of HCP?**

The hcp structure is very common for elemental metals and some examples include beryllium, cadmium, magnesium, titanium, zinc and zirconium.