Phase separation is the creation of two distinct
phases from a single
homogeneous mixture
In chemistry, a mixture is a material made up of two or more different chemical substances which are not chemically bonded. A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the ...
. The most common type of phase separation is between two
immiscible liquids, such as oil and water.
Colloid
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend ...
s are formed by phase separation, though not all phase separations forms colloids - for example oil and water can form separated layers under gravity rather than remaining as microscopic droplets in suspension.
Phase separation in cold gases
A mixture of two
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
isotopes (
helium-3
Helium-3 (3He see also helion) is a light, stable isotope of helium with two protons and one neutron (the most common isotope, helium-4, having two protons and two neutrons in contrast). Other than protium (ordinary hydrogen), helium-3 is the ...
and
helium-4
Helium-4 () is a stable isotope of the element helium. It is by far the more abundant of the two naturally occurring isotopes of helium, making up about 99.99986% of the helium on Earth. Its nucleus is identical to an alpha particle, and consis ...
) in a certain range of temperatures and concentrations separates into parts. The initial mix of the two isotopes spontaneously separates into
^He-rich and
^3He-rich regions. Phase separation also exists in
ultracold gas systems. It has been shown experimentally in a two-component
ultracold Fermi gas
An ideal Fermi gas is a state of matter which is an ensemble of many non-interacting fermions. Fermions are particles that obey Fermi–Dirac statistics, like electrons, protons, and neutrons, and, in general, particles with half-integer spin. ...
case. The phase separation can compete with other phenomena as
vortex lattice formation or an exotic
Fulde-Ferrell-Larkin-Ovchinnikov phase.
See also
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Biomolecular condensate
In biochemistry, biomolecular condensates are a class of membrane-less organelles and organelle subdomains, which carry out specialized functions within the cell. Unlike many organelles, biomolecular condensate composition is not controlled by a ...
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Colloid
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend ...
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Phase diagram
A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions (pressure, temperature, volume, etc.) at which thermodynamically distinct phases (such as solid, liquid or gaseous ...
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Spinodal decomposition
Spinodal decomposition is a mechanism by which a single thermodynamic phase spontaneously separates into two phases (without nucleation). Decomposition occurs when there is no thermodynamic barrier to phase separation. As a result, phase separatio ...
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Cahn–Hilliard equation The Cahn–Hilliard equation (after John W. Cahn and John E. Hilliard) is an equation of mathematical physics which describes the process of phase separation, by which the two components of a binary fluid spontaneously separate and form domains pu ...
References
Further reading
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{{chemical solutions
Equilibrium chemistry
Solvents
Condensed matter physics