Fundamentals of Materials Science and Engineering: An Integrated Approach, 3e

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).]