crystal structure model of Gallium Arsenide

Large crystal structure model of Gallium Arsenide with the unit cell highlighted and specific crystal faces on the surface

 

crystal structure model of silicon

...and a similar crystal structure model of silicon

 

 

Crystal structure models

lattice planes and faces

 

Crystal structure models are perfect for illustrating the concept of lattice planes and faces. The ability of a teacher to rapidly rotate a model, to indicate a plane and its relation to the unit cell, or to ask the student to locate a plane cannot be emulated in any other medium. In this respect, they are far more powerful than computer images.

 

This functionality can be enhanced by building crystal structure models that are designed specifically for teaching this aspect of crystal structure.

 

The simplest approach is to build a large model and to terminate the structure with specific crystallographic faces. Crystal structure models are almost always terminated with their {100}, {010} and {001} faces, but this does not have to be the case. One common model that we make with this approach is the diamond structure and its derivatives such as the sphalerite structure. This can readily be made in a compact model that incorporates the {100}, {110} and {111} planes and their symmetry-related equivalents. But, we can take the same approach with other structures to show whatever crystal faces you require.

 

An alternative approach is to incorporate acrylic lattice planes into unit cells or other crystal structure models. One advantage of this is that it is possible to make up smaller models to illustrate how the planes relate to the unit cell. But there is no limit to the size - it is equally possible to incorporate acrylic crystallographic planes into larger models.

 

Crystal planes highlighted in primitive unit cells

Primitive unit cells with acrylic lattice planes incorporated.

 

 

crystal structure model of sphalerite structure with alternative unit cells highlighted

A crystal structure model of the sphalerite structure with alternative unit cells highlighted

 

Crystal structure model of ZnO showing specific crystal faces

crystal structure model of zinc oxide with very specific faces indicated on its surface