Phase transition

A phase transition is a change between distinct physical states of matter as conditions such as temperature or pressure vary. It can involve abrupt changes in properties such as density, symmetry, or heat capacity.

Latent heat: Energy absorbed or released during a phase change without changing temperature at constant pressure. First-order transitions exchange latent heat as matter changes phase.
Thermodynamic phase: A region of matter with uniform physical properties and a distinct thermodynamic state. A phase transition changes which thermodynamic phase describes the material.
Melting: The transition from a solid to a liquid, usually caused by heating or lowering pressure. It is a familiar first-order transition with a latent heat.
First-order phase transition: A phase transition with discontinuous first derivatives of free energy and typically nonzero latent heat. Melting and boiling commonly belong to this discontinuous class.
Shape-memory alloy: A metal alloy that recovers a trained shape through a reversible solid-state transformation. Its useful motion comes from temperature-driven structural phase changes.
Critical point: The endpoint of a coexistence curve, beyond which distinct liquid and gas phases are no longer distinguishable. At this endpoint, the liquid–gas distinction vanishes and the transition becomes continuous.
Gibbs free energy: A thermodynamic potential that determines equilibrium at constant temperature and pressure. The stable phase minimizes Gibbs free energy under these conditions.
Boiling: The rapid formation of vapor bubbles throughout a liquid when its vapor pressure reaches the surrounding pressure. It exemplifies liquid–gas coexistence ending at a critical point.
Continuous phase transition: A transition without latent heat, where an order parameter changes continuously while response functions may become singular. It contrasts with transitions marked by a finite jump in entropy or density.
Liquid crystal: A state of matter with fluidity like a liquid and some orientational order like a crystal. Its intermediate phases enable electrically controlled optical behavior in displays.

Linked from 83 pages