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:
“A pregnant woman and her spouse dream of three babies—the perfect four-month-old who rewards them with smiles and musical cooing, the impaired baby, who changes each day, and the mysterious real baby whose presence is beginning to be evident in the motions of the fetus.”
—T. Berry Brazelton (20th century)
“A crystal of breath,
your irreversible
witness.”
—Paul Celan [Paul Antschel] (1920–1970)