Ionic conductivity (denoted by ) is a measure of a substance's tendency towards ionic conduction. Ionic conduction is the movement of

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

s. The phenomenon is observed in solids and solutions. Ionic conduction is one mechanism of

current Currents, Current or The Current may refer to: Science and technology * Current (fluid), the flow of a liquid or a gas ** Air current, a flow of air ** Ocean current, a current in the ocean *** Rip current, a kind of water current ** Current (stre ...

In crystalline solids

In most solids, ions rigidly occupy fixed positions, strongly embraced by neighboring atoms or ions. In some solids, selected ions are highly mobile allowing ionic conduction. The mobility increases with temperature. Materials exhibiting this property are used in batteries. A well-known ion conductive solid is β''-alumina ("BASE"), a form of aluminium oxide that has channels through which sodium cations can hop. When this

ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...

is complexed with a mobile

, such as Na⁺, it behaves as so-called

fast ion conductor In materials science, fast ion conductors are solid conductors with highly mobile ions. These materials are important in the area of solid state ionics, and are also known as solid electrolytes and superionic conductors. These materials are usefu ...

. BASE is used as a

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. B ...

in several types of

molten salt Molten salt is salt which is solid at standard temperature and pressure but enters the liquid phase due to elevated temperature. Regular table salt has a melting point of 801 °C (1474°F) and a heat of fusion of 520 J/g.< ...

electrochemical cell An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. The electrochemical cells which generate an electric current are called voltaic o ...

In glasses

Ion conduction in disordered solids like glasses, polymers, nanocomposites, defective crystals and other disordered solids plays an important role in technology.'

History

Ionic conduction in solids has been a subject of interest since the beginning of the 19th century.

Michael Faraday Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic inducti ...

established in 1839 that the laws of

electrolysis In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...

are also obeyed in ionic solids like

lead(II) fluoride Lead(II) fluoride is the inorganic compound with the formula Pb F2. It is a white solid. It exists as both an orthorhombic and cubic forms. Uses Lead(II) fluoride is used in low melting glasses, in glass coatings to reflect infrared rays, ...

() and

silver sulfide Silver sulfide is an inorganic compound with the formula . A dense black solid, it is the only sulfide of silver. It is useful as a photosensitizer in photography. It constitutes the tarnish that forms over time on silverware and other silver obje ...

(). In 1921, solid

silver iodide Silver iodide is an inorganic compound with the formula Ag I. The compound is a bright yellow solid, but samples almost always contain impurities of metallic silver that give a gray coloration. The silver contamination arises because AgI is hig ...

() was found to have had extraordinary high ionic conductivity at temperatures above 147 °C, AgI changes into a phase that has an ionic conductivity of ~ 1 –1 cm⁻¹. This high temperature phase of AgI is an example of a

superionic conductor In materials science, fast ion conductors are solid conductors with highly mobile ions. These materials are important in the area of solid state ionics, and are also known as solid electrolytes and superionic conductors. These materials are usefu ...

. The disordered structure of this solid allows the Ag⁺ ions to move easily. The present record holder for ionic conductivity is the related material Ag₂HgI₄. β''-alumina was developed at the

Ford Motor Company Ford Motor Company (commonly known as Ford) is an American multinational automobile manufacturer headquartered in Dearborn, Michigan, United States. It was founded by Henry Ford and incorporated on June 16, 1903. The company sells automobi ...

in the search for a storage device for

electric vehicle An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...

s while developing the

sodium–sulfur battery A sodium–sulfur battery is a type of molten-salt battery constructed from liquid sodium (Na) and sulfur (S). This type of battery has a high energy density (its energy density is 5 times that of a lead-acid battery), high efficiency of charge/ ...

References

External links

J Chem Phys
Physical quantities Electrochemistry {{electrochem-stub

In crystalline solids

In glasses

History

See also

References

External links