PY3090Preparation of MaterialsLecture 2

Colm Stephens

School of Physics

(Primitive)Cubic

• e.g. Mn

Body Centred Cubic (BCC)

• e.g. -Fe, V, Cr, Mo, W

Face CentredCubic (FCC)• e.g. -Fe,

Al, Ni, Cu,Ag, Pt, Au

Hexagonal Close Packed (HCP)• e.g. Be, Mg, -Ti, Zn, Zr

HCP Unit cell – plan view 1st layer

ratrat

HCP Unit cell – plan view 2nd layer

ratrat

HCP Unit cell – side view 2 layers

rat

C/2

HCP reduced sphere view

h

Close Packing FCC vs. HCP

Caesium chloride Cubic

• (Primitive) cubic

Sodium chloride FCC

Cristobolite FCC• e.g. SiO2

Diamond cubic (FCC)

• e.g. Si, Ge,grey-Sn

Zinc blende(FCC)• e.g. GaAs,

AlP, InSb(III-V SCs)ZnS, CdS,HgTe(II-VI SCs)

Carbon polymorphism• Graphite

Carbon polymorphism• Buckminster

Fullerene C60

• Carbon nanotube

Imperfections• Point defects

Lattice strains

TensileCompressive

Notice lattice strains• Point defects

Edge Dislocation

Burgers Vector5

4

4

4

1

Screw Dislocation

Mixed Dislocation