Perfect crystal
line materials are made up of solid regions of ordered matter. These regions are known as crystals. A perfect crystal is the one that contains no point, linear, or planar imperfections. There is a wide variety of crystallographic defects.
The hypothetical concept of a perfect crystal is important in the basic formulation of the third law 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 by various thermodynamic processes.
