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## What is the edge length of HCP?

Answer: For hcp lattice the edge length is equal to 4 atoms per unit and hexagonal closest packed is number of the 12 and it hold 6 atoms per units.

How is hcp density calculated?

The ratio of atomic sphere volume to unit cell volume, assuming a hard sphere model. Magnesium is hcp with c/a =1.624, density = 1.74g/cm^3.

### What is the unit cell of HCP?

The hexagonal closest packed (hcp) has a coordination number of 12 and contains 6 atoms per unit cell. The face-centered cubic (fcc) has a coordination number of 12 and contains 4 atoms per unit cell.

What is height of HCP?

In the calculation of packing efficiency of hcp arrangement,the height of the unit cell is taken as 4r. 2/3.

#### How do you find the height of HCP?

In the calculation of packing efficiency of hcp arrangement, the height of the unit cell is taken as 4r√2/3.

What is the length of a unit cell?

In general, a unit cell is defined by the lengths of three axes (a, b, and c) and the angles (α, β, and γ) between them, as illustrated in Figure 10.55. The axes are defined as being the lengths between points in the space lattice. Consequently, unit cell axes join points with identical environments.

## How do you calculate unit cell?

We measure up the mass of one unit cell to the mass of all the atoms present in that same cell. The number of atoms is going to depend on the type of cell it is. So we multiply the number of atoms “n” into the mass of each atom “m” to achieve the mass of a unit cell.

Is hcp and fcc same?

They are called face-centered cubic (fcc) (also called cubic close packed) and hexagonal close-packed (hcp), based on their symmetry. Both are based upon sheets of spheres arranged at the vertices of a triangular tiling; they differ in how the sheets are stacked upon one another.

### What is C a ratio in hcp?

Show that the c/a ratio for an ideal hexagonal close-packed structure is √8/3 = 1.633. If c/a is significantly larger than this value, the crystal structure may be thought of as composed of planes of closely packed atoms, the planes being loosely packed.

Which is the most symmetric unit cell?

the most symmetrical one is the cubic system and the least symmetrical is the triclinic one.

#### What is the height of an HCP unit cell?

How is the packing density of a HCP determined?

The volume of the unit cell of the HCP = base area x height Thus the packing density is 74% and hence, it is a closed packed structure.

## Which is the unit cell of hcp structure?

The unit cell for the hcp structure is the hexagonal cell, which is illustrated in the virtual reality display shown below. The positions of the individual magnesium nuclei are shown by small dots. The magnesium atoms or sections of magnesium atoms are shown by the spheres or sphere sections.

Which is the ideal ratio for a HCP structure?

HCP STRUCTURE •ideal ratio c/a of 8/3 1.633 •unit cell is a simple hexagonal lattice with a two-point basis (0,0,0) (2/3,1/3,1/2) a a Plan view •{0002} planes are close packed •ranks in importance with FCC and BCC Bravais lattices 72

### How to calculate the density of a hexagonal structure?

U §· ¨¸ ©¹ n: number of atoms/unit cell A: atomic mass V C : volume of the unit cell N A: Avogadro’s number (6.023×1023atoms/mole) Calculate the density of copper.