Module 4 : Solid State Chemistry
Lecture 16 : Lattices and Unit Cells
 
 

Table 16.1 Essential symmetries of the seven crystal systems.

 

Sr no

System

Symmetries

     

1

Cubic

four C3 axes tetrahedrally arranged

     

2

Hexagonal

one C6 axes

     

3

Tetragonal

one C4 axes

     

4

Rhombohedral

one C3 axes

     

5

Orthorhombic

three perpendicular C2 axes

     

6

Monoclinic

one C2 axes

     

7

Triclinic

none ! or only C1 axes

 

The seven cubic systems can also be classified in terms of the relations between their unit cell parameters a, b, c and , and . These relations are shown in Table 16.2


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