CH1. CRYSTALS AND CRYSTAL STRUCTURES
keywords: axes, inter-axial angles (alpha for b and c, beta for c and a, and gamma for a and b)1. Seven crystal systems
Cubic, Tetragonal, Orthorhombic, Monoclinic, Triclinic, Hexagonal, Trigonal(Rhombohedra).Rhombohedra crystal is often more conveniently described in terms of hexagonal crystal.
PbTiO3, tetragonal---> cubic
BaTiO3, rhombohedra ---> orthorhombic ---> tetragonal---> cubic
BiFeO3, Rhombohderal (Hexagonal)
2. Strukturbericht symbols for simple structure types
A1: cubic-close packed, face-centered cubic
Copper, Cu
A2: body-centered cubic
Tungsten, W
A3: hexagonal close-packed
(0,0,0), (1/3, 2/3, 1/2)
Magnesium, Mg
Halite: MX
Sodium chloride, NaCl
Rutile, MX2
titanium oxide, TiO2
Ti: 0, 0, 0; 0.5, 0.5, 0.5,
O: 0.3, 0.3, 0.0
0.8, 0.2, 0.5
0.7, 0.7, 0.0
0.2, 0.8, 0.5
Fluorite, MX2
calcium fluroite, CaF2,
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