|
Diamond Structures
- Formation
Diamonds are formed when extreme heat (temperatures of 2200
degrees Fahrenheit) and extreme pressure cause carbon atoms to
crystallize forming diamonds approximately ninety miles under the
earth's surface. Diamonds reach the surface of the earth via volcanic
channels. Diamonds are
deposited on the surface of the earth when a volcano erupts. Diamonds
are the hardest of all known bodies scoring a level of 10 (harder than
steel) on the Mohs Hardness Scale.
Diamond Structures
A Diamond is a clear transparent precious gem stone
made totally of Carbon atoms (Chemical Composition 'C') crystallised
in a cubic (isometric) arrangement which has been highly compressed over
millions of years.
A diamond can also be described as a transparent crystal of tetrahedral
shaped bonded carbon atoms. A tetrahedron is composed of four triangular
faces, three of which meet at each vertex. The tetrahedral arrangement of
atoms is the source of many of diamond’s properties. A crystal structure
is composed of a unit cell which is a set of atoms arranged in a
particular way. These are periodically repeated in three dimensions on a
lattice. The spacing between unit cells is called the lattice parameters.
Diamond Crystal Structures
Diamonds are a natural product which usually present the form of crystals.
The crystals are more or less regular and perfect in their development.
These forms of crystals belong to the group of geometrical solids known to
crystallographers as the Cubic or Isometric system. The unit
cell of diamond has a two atom basis in which half of the atoms are at lattice points.
Diamond crystal structures and symmetry play a role in determining many of
its properties including cleavage, electronic band structure and optical
properties.
Formation of Diamond
Structures
- Common Forms
The most common forms of diamond structures are the regular octahedron and the rhombic dodecahedron ; the former bounded by eight equilateral triangles, and the latter by twelve rhomb's, or lozenge-shaped surfaces
or structures. The faces of the crystals are often more or less curved, or convex
structures, whilst those of other crystalline bodies, with few exceptions, are flat
structures. Diamonds commonly take the form of a six-faced octahedron,
which, by the rounding of its eight-and-forty faces becomes almost
spherical or approaches a small ball in structure.
Structures of Diamonds and Graphite
The Carbon Element exists freely as graphite and diamond and is obtained
from burning with insufficient oxygen. As previously stated the tetrahedral arrangement of atoms is the source of many of diamond’s
properties. However the carbon atoms in Graphite display a different (non- tetrahedral) connectivity and as a
result shows completely different physical characteristics. Graphite
is therefore very different to a diamond and is a soft, dark gray,
opaque mineral.
Graphite Diamonds -
Structure - Graphite -
Guide - Crystal Structures
Diamond Structures
|
