3. Structural Properties

• Short range, but no long range order

• Similar to the structure of liquids

• Example: Glass

Atoms or molecules are arranged ina regular pattern with a long range order

a theoretical construct,a geometric arrayof points in space.

the atoms thatare placed at the lattice points

smallest volume elementthat by repetition in 3D describesthe crystal

• region of space that is closer to a lattice point than any other

• smallest possible primitive cell.

1. Draw lines from the latticepoint to all others

2. At the midpoint and normalto these lines, draw new lines(planes in 3D).

3. Take the smallest polyhedron

1. Determine the intercept of the plane on the three crystal axes

2. Take the reciprocals of these intercepts

3. Convert the reciprocals into the 3 smallest integers

Atoms per unit cell/Volume of unit cell

mass of atoms in unit cell/Volume of unit cell

lamda = wave length

• X-rays

• Electrons

• Neutrons

• Charge density

• weak interaction

• not very good for light atoms

• use in air

• Charge interaction

• very strong

• only penetrates a few atomiclayers, gives only surface information

• need to use in vacuum

• Mainly interacts with mass

• Can use with light atoms

• Additional magnetic information

• Very expensive