Crystalline Solids Crystal Lattices and Unit Cells

Crystalline Solids Crystal Lattices and Unit Cells  

The copper atoms have been shrunk so that the crystal structure is more visible.The crystal lattice is the geometric arrangement of lattice points, which you can take to be the centers ofthe atoms. Lines have been drawn to emphasize the geometry ofthe lattice. 

In the same way, you can divide any crystal lattice into boxlike cells, or unit cells. The unit cell of a crystal is the smallest boxlike unit (each box having faces that are parallelograms) from which you can imagine constructing a crystal by stacking the units in three dimensions. 

Most of the crystal systems have more than one possible crystal lattice. A simple (or primitive) lattice has a unit cell in which there are lattice points only at the comers of the unit cell. Other lattices in the same crystal system have additional lattice points either within the body of the unit cell or on faces of the unit cell. As an example, we will describe the cubic crystal system in some detail. 

Unit-cell shapes of the different crystal systems 

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