phenomenon

first order phase transition

A discontinuous transition between states of matter or systems, occurring abruptly at a specific threshold.
17 related articles

Description

A first-order phase transition is a sudden, discontinuous change in a system's state at a specific threshold of temperature, pressure, or another external parameter. Unlike smooth, continuous transitions, first-order transitions involve an abrupt jump in properties like density, entropy, or magnetization, accompanied by the release or absorption of latent heat. Classic examples include boiling water, melting ice, and the sudden appearance of superconductivity in certain materials at their critical temperature.

History

The concept was formalized in the late 19th century by Paul Ehrenfest, who classified phase transitions by the order of discontinuity in thermodynamic derivatives. The term 'first-order' refers to the first derivative of the free energy (e.g., entropy or volume) being discontinuous.

How it works

During a first-order transition, the system passes through a mixed phase where regions of the old and new states coexist. The transition occurs when the free energy of the new phase becomes lower than that of the old phase, but a barrier prevents spontaneous conversion. The system must overcome this barrier via nucleation — small fluctuations create seeds of the new phase, which then grow if they exceed a critical size. This is why supercooled water can remain liquid below freezing until a disturbance triggers rapid crystallization.

In practice

First-order transitions are exploited in heat storage materials (phase-change materials), in shape-memory alloys used in actuators, and in understanding geological processes like magma crystallization. They also underpin the operation of many thermal switches and sensors.

Fun fact

In a first-order transition, the system can exhibit hysteresis — the transition temperature differs depending on whether you are heating or cooling, because the system gets 'stuck' in the metastable phase.

Related articles · 17

Mesoscale2026-08-091 minarXiv:2608.08697express
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HEP Phenomenology2026-08-051 minarXiv:2608.04598express
A Collision That Heats the Vacuum
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General Relativity2026-08-031 minarXiv:2608.02736express
A Jump Instead of a Smooth Slide: How Neutron Stars Give Themselves Away
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The Conductor's Baton: How a Phase Transition Creates Axion Dark Matter
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Materials2026-06-273 minarXiv:2606.29055
Diamond Storm: Birth of Quantum Vortices from the Void
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Superconductivity2026-06-251 minarXiv:2606.27040express
The Phase Transition Nobody Noticed
The nickelate family consists of layered crystals, like a stack of pancakes: nickel and oxygen layers alternate with lanthanum spacers. Two years ago, superconductivity was discovered in them — the ability to conduct electricity without resistance when cooled.
How Squeezing Rubber Gives Rise to Elusive Angles
A sheet of rubber is squeezed from two sides. At first glance, it's just deformation. But inside, deep within the material, a hidden order awakens. This is not just wrinkles on the surface. It's the birth of special zones where vibrations become trapped, as if in a cage. Previously, it was thought that such effects require intricate lattices and periodic structures.
Nuclear Theory2026-06-041 minarXiv:2606.06378express
Neutron Stars: Frozen on the Verge of a Phase Change
Neutron stars are cosmic 'ice cubes' of unimaginable density: a tablespoon of their material would outweigh Mount Everest. It was a mystery what lay in their cores: ordinary neutron matter (a giant atomic nucleus) or exotic quark matter, where particles are not bound into neutrons.
Cosmic sous-vide: How slow reheating resurrects primordial black holes
In the seething cauldron of the early universe, the vacuum, like a supercooled liquid, could boil with bubbles of a new phase. For a long time, physicists pinned their hopes on these bubbles as a source of primordial black holes (PBHs)—ideal candidates for dark matter.
Statistical Mech2026-05-092 minarXiv:2605.08967express
When Disorder Gives Birth to Order
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HEP Theory2026-04-191 minarXiv:2604.17216express
Bubbles in a Superfluid
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q-bio.PE2026-04-172 minarXiv:2604.16065express
Microbes at the Edge of a Breakdown
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General Relativity2026-04-021 minarXiv:2604.01818express
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Materials2026-03-261 minarXiv:2603.25429express
Magnetic Cold: Measuring Cooling with a Single Device
The magnetic refrigerator of the future won't hum with a compressor. Instead, it will cool your groceries by exploiting a special material that heats up in a magnetic field and cools down when the field is removed. This cycle resembles the compression and expansion of gas in a conventional fridge, but here a magnet does the work of a piston.
Quantum Gases2026-03-071 minarXiv:2603.07121express
Order from Chaos: How Heat Gives Birth to a Crystal
Water in a pot, when heated, doesn't boil: it turns into ice. That's roughly how ultracold atoms behave in an optical lattice — a light-based crystalline grid that holds atoms in place. Scientists simulated this system on a computer to understand how order changes as temperature rises.
Quantum Physics2025-11-061 minarXiv:2511.04028express
Heat in Reverse: When Hot Freezes from Cold
Water always flows downhill, and heat from hot to cold. That's what энтропия dictates. But the quantum world finds loopholes. Physicists made light particles interact with hot and cold environments in an uncertain sequence — like a flipped coin that hasn't landed yet.
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An orchestra without a conductor plays a complex piece. The listener hears the overall music but wants to understand who leads the melody and who merely echoes it in unison.