Crystalline materials (mainly metals and alloys, but also stoichiometric salts and other materials) are made up of solid regions of ordered matter (atoms placed in one of a number of ordered formations called Bravais lattices). These regions are known as crystals. A perfect crystal is one that contains no point, linear, or planar imperfections. There are a wide variety of crystallographic defects.
The hypothetical concept of a perfect crystal is important in the basic formulation of the laws of thermodynamics.
In crystallography, the phrase 'perfect crystal' can be used to mean "no line or planar defects", as it is difficult to measure small quantities of point defects in an otherwise defect-free crystal.
Imperfections are created due to gravity. In space and in zero gravity environments perfect crystals can be created as on the International Space Station.
Famous quotes containing the words perfect and/or crystal:
“He is the old hunting dog of the sea
who in the morning will rise from it
and be undrowned
and they will take his perfect green body
and paint it red.”
—Anne Sexton (1928–1974)
“We have ... a thirst unquenchable, to allay which he has not shown us the crystal springs. This thirst belongs to the immortality of Man.... It is no mere appreciation of the Beauty before us—but a wild effort to reach the Beauty above.”
—Edgar Allan Poe (1809–1849)