The beauty and symmetry of crystals have fascinated people for thousands
of years. Somehow, they seem different from more ordinary matter. However,
most solid objects are made of many tiny interlocking crystals. It is only
occasionally that the individual crystals are large enough to catch our
attention, as in these beautiful examples.
Celestite
Sulfur
Pyrite
The above images are the property of Amethyst
Galleries, Inc., and may not be copied for commercial purposes.
Permission to copy descriptions and images is granted
for personal and educational use only.
Refer to http://mineral.galleries.com/
The lattice can have a profound influence on the material's properties. For example, below we see two crystals - graphite and diamond. They each contain only 1 kind of atom - carbon. The difference is in how those atoms are arranged.
Graphite
Diamond
The above images are the property of Amethyst Galleries,
Inc., and may not be copied for commercial purposes.
Permission to copy descriptions and images is granted
for personal and educational use only.
Refer to http://mineral.galleries.com/
Graphite is black, soft, and an excellent lubricant. This suggests that it must be easy to separate atoms in graphite, or at least to make them slide past one another.
Diamond is transparent, strong, and very hard. It is a superb cutting tool. The atoms in diamond must be very strongly held in position.
Chemically, diamond is inert. Graphite, on the other hand, is very useful for absorbing and catalyzing reactions. The structures of diamond and graphite explain these differences.
The carbon atoms in diamond are each bound to 4 others in a 3-dimensional network. To change the shape of a diamond or break it requires that many of these strong bonds be broken simutaneously. Since there is little room for other molecules to get into the structure, diamond is not very reactive.
Shown below is an STM image of a graphite surface. This is an actual image, not a simulation. It clearly shows the interconnected 6-membered rings of graphite and the triangular geometry about each carbon atom.
Used with permission TopoMetrix Corporation
5403 Betsy Ross Drive, Santa Clara, CA 95054
Boron nitride also exists in two different crystalline structures.
Click on each image below to view that structure.
Hexagonal Boron Nitride Cubic
Boron Nitride
Click
here to go to next page.
Structure
of Crystals
Crystal Lattices
Unit Cells
From Unit Cell to Lattice
From Lattice to Unit Cell
Stoichiometry
Packing & Geometry
Simple Cubic Metals
Close Packed Structures
Body Centered Cubic
Cesium Chloride
Sodium Chloride
Rhenium Oxide
Niobium Oxide
Except as otherwise noted, all images, movies and
VRMLs are owned and copyright
by
Barbara L. Sauls and Frederick C. Sauls 2000.
Contact the owners for individual permission to
use. blsauls@kings.edu