Galinstan (R) is a brand name for a
alloy
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
composed of
gallium
Gallium is a chemical element with the symbol Ga and atomic number 31. Discovered by French chemist Paul-Émile Lecoq de Boisbaudran in 1875, Gallium is in group 13 of the periodic table and is similar to the other metals of the group (aluminiu ...
,
indium
Indium is a chemical element with the symbol In and atomic number 49. Indium is the softest metal that is not an alkali metal. It is a silvery-white metal that resembles tin in appearance. It is a post-transition metal that makes up 0.21 parts p ...
, and
tin
Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal.
Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
which melts at and is thus liquid at room temperature.
However, it is not a eutectic alloy but a near eutectic alloy.
In scientific literature, galinstan is also used as an acronym denoting the eutectic composition of the alloy of Ga-In-Sn, which melts at around .
The composition of both alloys is roughly the same, albeit the Galinstan (R), the technical product of a company, has likely additions of flux to improve flowability, reduce melting temperature, and reduce surface tension. The physical properties of the Galinstan (R) and the pure eutectic alloy EGaInSn thus differ slightly.
Galinstan is composed of 68.5%Ga, 21.5%In, and 10.0%Sn (by weight).
Due to the low toxicity and low reactivity of its component metals, in many applications, galinstan has replaced the toxic liquid
mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
or the reactive
NaK
In data networking, telecommunications, and computer buses, an acknowledgment (ACK) is a signal that is passed between communicating processes, computers, or devices to signify acknowledgment, or receipt of message, as part of a communicatio ...
(
sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
–
potassium
Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...
alloy).
Name
The name "Galinstan" is a
portmanteau
A portmanteau word, or portmanteau (, ) is a blend of words[Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...](_blank)
for "tin"). The brand name "Galinstan" is a
registered trademark
The registered trademark symbol, , is a typographic symbol that provides notice that the preceding word or symbol is a trademark or service mark that has been registered with a national trademark office. A trademark is a symbol, word, or word ...
of the
German
German(s) may refer to:
* Germany (of or related to)
** Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ge ...
company .
Physical properties
*Boiling point: >1300°C
*
Vapour pressure
Vapor pressure (or vapour pressure in English-speaking countries other than the US; see spelling differences) or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases ...
: <10
−8Torr
The torr (symbol: Torr) is a unit of pressure based on an absolute scale, defined as exactly of a standard atmosphere (). Thus one torr is exactly (≈ ).
Historically, one torr was intended to be the same as one "millimeter of mercury ...
(at 500°C)
*Solubility: Insoluble in water or organic solvents
*
Viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water.
Viscosity quantifies the inte ...
: 0.0024
Pa·
s (at 20°C)
*
Thermal conductivity
The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa.
Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...
: 16.5
W·m
−1·
K−1
*
Electrical conductivity
Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...
: 3.46×10
6 S/m (at 20°C)
*
Surface tension
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to f ...
: ''s'' = 0.535–0.718 N/m (at 20°C, dependent on producer)
Unlike mercury, galinstan tends to
wet and adheres to many materials, including glass, which can limit its use as a direct replacement material in some situations.
Uses
The non-toxic galinstan replaces mercury in
thermometers
A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass thermomete ...
; the tube interior must be coated with
gallium oxide to prevent it from
wetting
Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. This happens in presence of a gaseous phase or another liquid phase not miscible with th ...
the glass.
Galinstan has higher reflectivity and lower density than mercury. In
astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...
, it can replace mercury in
liquid-mirror telescope
Liquid-mirror telescopes are telescopes with mirrors made with a reflective liquid. The most common liquid used is mercury, but other liquids will work as well (for example, low-melting alloys of gallium). The liquid and its container are rotated ...
s.
Metals or alloys like galinstan that are liquids at room temperature are often used by
overclockers
In computing, overclocking is the practice of increasing the clock rate of a computer to exceed that certified by the manufacturer. Commonly, operating voltage is also increased to maintain a component's operational stability at accelerated spe ...
and enthusiasts as a
thermal interface for computer hardware cooling, where their higher thermal conductivity compared to thermal pastes, and thermal epoxies can allow slightly higher clock speeds and CPU processing power achieved in demonstrations and competitive overclocking. Two examples are Thermal Grizzly Conductonaut and Coolaboratory Liquid Ultra, with thermal conductivities of 73 and 38.4 W/mK respectively. Unlike ordinary thermal compounds which are easy to apply and present a low risk of damaging hardware, galinstan is electrically conductive and causes
liquid metal embrittlement
Liquid metal embrittlement (LME), also known as liquid metal induced embrittlement, is a phenomenon of practical importance, where certain ductile metals experience drastic loss in tensile ductility or undergo brittle fracture when exposed to speci ...
in many metals including aluminum which is commonly used in heatsinks. Despite these challenges the users who are successful with their application do report good results. In August 2020,
Sony Interactive Entertainment
Sony Interactive Entertainment (SIE), formerly known as Sony Computer Entertainment (SCE), is a multinational video game industry, video game and digital entertainment company wholly owned by multinational conglomerate Sony. The SIE Group is ma ...
patented a galinstan-based thermal interface solution suitable for mass production, for use on the
PlayStation 5
The PlayStation 5 (PS5) is a home video game console developed by Sony Interactive Entertainment. Announced as the successor to the PlayStation 4 in April 2019, it was launched on November 12, 2020, in Australia, Japan, New Zealand, North Ame ...
.
Galinstan is difficult to use for cooling fission-based
nuclear reactor
A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu ...
s, because indium has a high
absorption cross section
Absorption cross section is a measure for the probability of an absorption process. More generally, the term cross section is used in physics to quantify the probability of a certain particle-particle interaction, e.g., scattering, electromagne ...
for
thermal neutron
The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with ...
s, efficiently absorbing them and inhibiting the fission reaction. Conversely, it is being investigated as a possible coolant for fusion reactors. Its nonreactivity makes it safer than other liquid metals, such as
lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ...
and
mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
.
Galinstan is used as a liquid, deformable conductor in soft robotics and stretchable electronics. Galinstan can be used to replace wires, interconnects, and electrodes as well as the conductive element in inductor coils and dielectric composites for soft capacitors.
X-ray equipment
Extremely high-intensity sources of 9.25 keV X-rays (gallium K-alpha line) for X-ray phase microscopy of fixed tissue (such as mouse brain), from a focal spot about 10 μm × 10 μm, and 3-D
voxel
In 3D computer graphics, a voxel represents a value on a regular grid in three-dimensional space. As with pixels in a 2D bitmap, voxels themselves do not typically have their position (i.e. coordinates) explicitly encoded with their values. Ins ...
s of about one cubic micrometer, may be obtained with an X-ray source that uses a liquid-metal galinstan anode. The metal flows from a nozzle downward at a high speed, and the high-intensity electron source is focused upon it. The rapid flow of metal carries current, but the physical flow prevents a great deal of anode heating (due to forced-convective heat removal), and the high boiling point of galinstan inhibits vaporization of the anode.
See also
*
Field's metal, has a table of low melting point alloys
*
Rose's metal
Rose's metal, Rose metal or Rose's alloy is a fusible alloy with a low melting point.
Rose's metal consists of 50% bismuth, 25–28% lead and 22–25% tin. Its melting point is between . The alloy does not appreciably contract or expand on solidif ...
*
Wood's metal
Wood's metal, also known as Lipowitz's alloy or by the commercial names Cerrobend, Bendalloy, Pewtalloy and MCP 158, is a metal alloy that is useful for soldering and making custom metal parts, but which is toxic to touch or breathe vapors from. ...
References
Sources
*
*{{cite journal , doi = 10.1002/adfm.200701216 , title = Eutectic Gallium-Indium (EGaIn): A Liquid Metal Alloy for the Formation of Stable Structures in Microchannels at Room Temperature , year = 2008 , last1 = Dickey , first1 = Michael D. , first2 = Ryan C. , first3 = Ryan J. , first4 = Emily A. , first5 = David A. , first6 = George M. , journal = Advanced Functional Materials , volume = 18 , pages = 1097 , last2 = Chiechi , last3 = Larsen , last4 = Weiss , last5 = Weitz , last6 = Whitesides , issue = 7, s2cid = 538906
Gallium alloys
Tin alloys