Metal crystal structure

Atoms in metal crystals can be regarded as rigid spheres, and the stacking methods are mainly hexagonal close-packed, vertical-centered close-packed, cube-centered close-packed, and diamond-typed
.

1.
Hexagonal Close Packing

The atoms in the metal crystal can be regarded as rigid spheres.
In a layer, the closest packing method is that a sphere is tangent to the surrounding 6 spheres, forming 6 recesses around the center.
This is the first layer ( Marked as A layer)
.

Every two layers form a cycle, which is the ABAB stacking method, stacking hexagonal prism-shaped units
.

Figure 6-46 Hexagonal close packing of metal crystals

2.

Vertically, the first and second layers of the core close-packed are the same as the hexagonal close-packed.
The third layer is to align the balls with the 2, 4, and 6 recesses of the first layer (denoted as layer C); the fourth layer repeats the first Layers; the vertical cores are densely stacked according to the three layers of ABCABC to form a cycle (Figure 6-47)
.

Figure 6-47 The vertical close-packing of metal crystals

From Fig.

Figure 6-48 The selection of a close-packed metal crystal unit cell on the vertical side

3.

In the close-packed cube center (Figure 6-49), the atom at the center of the cube is tangent to the 8 atoms at the vertices, and the atoms at the vertices of the cube are not tangent.
The space utilization rate is lower than that of the cube center and hexagonal stacking
.

Substituting all ions in the cubic zinc sulfide unit cell with carbon atoms, the diamond unit cell is obtained, and metals such as gray tin and germanium adopt a diamond-type accumulation method (Figure 6-49)
.

Figure 6-49 Cube-centered close packing and diamond-shaped packing