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
Burgers Vector5
4
4
4
1
Screw Dislocation
Mixed Dislocation