A
phase transition is the transformation of a
thermodynamic system from one
phase or
state of matter to another one by
heat transfer. The term is most commonly used to describe transitions between
solid,
liquid and
gaseous states of matter, and, in rare cases,
plasma. A phase of a
thermodynamic system and the states of matter have uniform physical properties. During a phase transition of a given medium certain properties of the medium change, often discontinuously, as a result of the change of some external condition, such as temperature, pressure, or others. For example, a liquid may become gas upon heating to the
boiling point, resulting in an abrupt change in
volume. The measurement of the external conditions at which the transformation occurs is termed the phase transition. Phase transitions are common in nature and used today in many technologies.