GTBL042-03 GTBL042-Callister-v2 September 7, 2007 11:56
62 • Chapter 3 / Structures of Metals and Ceramics
Table 3.6 Lattice Parameter Relationships and Figures Showing Unit Cell
Geometries for the Seven Crystal Systems
Axial
Crystal System Relationships Interaxial Angles Unit Cell Geometry
Cubic a=b=c α=β=γ= 90 ◦
a
a
a
Hexagonal a=b=c α=β= 90 ◦,γ= 120 ◦
a a a
c
Tetragonal a=b=c α=β=γ= 90 ◦
a
a
c
Rhombohedral
(Trigonal)
a=b=c α=β=γ= 90 ◦ aa
a
Orthorhombic a=b=c α=β=γ= 90 ◦
a
b
c
Monoclinic a=b=c α=γ= 90 ◦=β
a
b
c
Triclinic a=b=c α=β=γ= 90 ◦
b a
c
VMSE
Crystal Systems/Unit
Cells for Metals
Systems
Concept Check 3.2
What is the difference between crystal structure and crystal system?
[The answer may be found at http://www.wiley.com/college/callister (Student Companion Site).]