Difference between Hexagonal and Cubic close packing
In this article we have given detailed and main comparison between Hexagonal close packing and Cubic close packing.
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. | There are three layers of sphere placed one on the other, covering all octahedral holes by a third layer of sphere. |
Hexagonal close packing has tetrahedral and octahedral holes. | Cubic close packing has tetrahedral holes, but octahedral holes are covered by a layer of sphere. |
Volume of the hexagonal close packing unit cell is 24(2) ^1/2xr^3. | Volume of Cubic close packing unit cells is 16(r)^3/2.
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“ABA” arrangement is known as the hexagonal close. Packing (HCP) arrangement. | “ABC” arrangement is known as the cubic close packing (CCP) arrangement.
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Hexagonal close packing is based on a hexagonal unit cell with sides of equal length. | Cubic close packing is based on face centered cubic unit cells. |
The unit cell of hexagonal close packing has 6 spheres | The unit cell of cubic close packing has 4 spheres. |
Hexagonal close packing shows the ‘ABAB’ pattern. | Cubic close packing shows the ABCABC pattern. |
Arrangement of the sphere in the third layer exactly resembles the first layer. | Arrangement of the sphere in the third layer does not resemble those of either the first or second layer. |
Tetrahedral voids of the second layer are exactly covered by the sphere of the third layer. | Octahedral Voids of 2nd layer are Not exactly covered ( partially ) by the sphere of the third layer. |
Examples of the HCP Are: this type of packed lattice is found in many metals such as mg and Zn E.T.C. | Examples of the CCP are : These types of close packing of constituent particles are found in metal like silver, copper. |
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