Lattices

Take a periodic structure, choose reference points that are translationally equivalent (indistinguishable). They make up a lattice.

Example: here's an array of objects in a plane.

Lots of possible lattices: could pick any set of translationally equivalent points. Could pick this set of points.

Or this set of points:

In either case, if you concentrate on the points, you get this lattice.

Which can be connected by this set of lattice lines.

The areas included in the parallelograms defined by the lattice lines are the unit cells making up the crystal. These are the areas (volumes in 3-d space) that generate the entire crystal when translated and stacked along their axes.

back to index

next topic

previous topic

copyright © Ron Stenkamp stenkamp@u.washington.edu Most recent update 1/7/97