Buy Online: Diamond Crystallography
The crystal structure of diamond is a face-centred cubic (FCC) lattice, with a basis of two identical carbon atoms associated with each lattice point: one at (0, 0, 0) and the other at (1/4, 1/4, 1/4), where the coordinates are given as fractions along the cube sides. This is the same as two interpenetrating FCC lattices, each with atoms at only the latice points, offset from one another along a body diagonal by one-quarter of its length.
| Side Length, a0 | 3.567 Angstrom (0.3567 nm) |
| c -c Bond Strength | 1.54 Angstrom |
| Atomic Density | 1.76 x 1029 atoms / m3 |
| Packing Friction | 0.34 |
(at room temperature)
Crystal Orientations
Within the cubic lattice there are three major crystallographic planes of carbon atoms that can be used to describe its structure. The family of equivalent planes is denoted by braces: "{}".
The three major crystallographic planes are: -
The family of planes {100}, commonly known as the 4-point planes
The family of planes {110}, commonly known as the 2-point planes
The family of planes {111}, commonly known as the 3-point planes
Specific planes are denoted by brackets: "( )" e.g. (100) and specific directions are denoted by square brackets: "[ ]" e.g. [100]. The family of equivalent directions is denoted by arrow brackets: "<>".
As diamond is cubic, planes are perpendicular to directions i.e.
The planes of atoms impart different degrees of abrasiveness or ease of polishing depending on which orientation is presented to the work piece. The softest polishing direction in the {100} plane is the <100> direction. The hardest is the <111> direction in the {111}.
The image below shows a 3 dimensional cubic crystal with {100}, {110} and {111} faces.
The diagrams below show how these planes relate to a regular octrahedral crystal
