Crystallography

Space lattice

an infinite array of points in 3 d in which every point has the same surrounding indetical to that of every other point in the array

Unit cell

the smallest unit which, when repeated in space indefinetly, will generate a space lattice

Glass

is not a crystal because crystals are everything but transparent

how many distinguisable ways of arranging points are there

14 known as Bravais lattices

name the 3 basic configurations

Simple cubic (aka SC) 1 atom per unit cell

Body Centered Cubic (aka BCC) 2 atoms per unit cell

Face Centered Cubic (aka FCC) 4 atoms per unit cell

crystallography in real life

structures are not perfect → there are defects

→ point imperfections

→ line imperfections

→ surface imperfections

→ volume imperfections

Point imperfections

found in point-like regions of crystal

→ vacancy

→ subtitutional impurity

→ interstitial impurity

Line imperfections aka dislocations

cause lattice distortion centered around a line

→ edge dislocation (T shape symbol)

→ screw dislocation

Surface imperfections

regions of distortion that lie about the surface