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What is the APF of hcp?

What is the APF of hcp?

HCP is one of the most common structures for metals. 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%. HCP is a close-packed structure with AB-AB stacking.

What is APF in crystal structure?

In crystallography, atomic packing factor (APF), packing efficiency, or packing fraction is the fraction of volume in a crystal structure that is occupied by constituent particles. It is a dimensionless quantity and always less than unity.

How do I get APF from hcp?

c a = 8 3 = 1.633 2 Page 3 2. Show that the atomic packing factor for HCP is 0.74. Now, the unit cell volume is the product of the base area times the cell height, c.

Why do fcc and hcp have the same APF?

Because FCC and HCP are both composed of close-packed layers, they have the same type and number of interstitial sites–the only difference is the location of these interstitial sites. You already know that unit cells of metals are not fully packed (74% for FCC and HCP), which means they have some empty space.

How do you find APF?

Remember, APF is just the volume of the atoms within the unit cell, divided by the total volume of the unit cell. You use this to calculate the APF of any crystal system, even if it’s non-cubic or has multiple kinds of atoms!

How is APF calculated?

The atomic packing factor is defined as the ratio of the volume occupied by the average number of atoms in a unit cell to the volume of the unit cell. for FCC a = 2√2 r where a is side of the cube and r is atomic radius.

What is FCC BCC 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. The body-centered cubic (bcc) has a coordination number of 8 and contains 2 atoms per unit cell.

Why is APF important?

APF annual recognizes the Most Significant Futures Works for the purpose of identifying and rewarding the work of professional futurists and others whose work illuminates aspects of the future.

What is APF simple cubic?

The atomic packing factor [A.P.F]: It can be defined as the ratio between the volume of the basic atoms of the unit cell (which represent the volume of all atoms in one unit cell ) to the volume of the unit cell it self.

Is nickel a FCC?

Nickel is highly crystalline, having an FCC structure as shown below. Ni has an atomic radius of 0.1246 nm and a lattice parameter of 3.52 Angstroms. (FCC also gives a coordination number of 12 and an atomic packing factor of 0.74) The image below shows the basic unit of the FCC.

How many atoms are in FCC?

four atoms
FCC unit cells consist of four atoms, eight eighths at the corners and six halves in the faces.