Rubidium silver iodide is a ternary

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the formula RbAg₄I₅. Its conductivity involves the movement of

silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

ions within the crystal lattice. It was discovered by Dr. Boone Owens while searching for chemicals which had the ionic conductivity properties of alpha-phase

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 grey colouration. The silver contamination arises because some samp ...

at temperatures below 146 °C for AgI. RbAg₄I₅ can be formed by melting together or grinding together stoichiometric quantities of rubidium iodide and silver(I) iodide. The reported conductivity is 25

siemens Siemens AG ( ) is a German multinational technology conglomerate. It is focused on industrial automation, building automation, rail transport and health technology. Siemens is the largest engineering company in Europe, and holds the positi ...

per metre (that is a 1×1×10 mm bar would have a resistance of 400 ohms along the long axis). The crystal structure is composed of sets of iodine

tetrahedra In geometry, a tetrahedron (: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex (geometry), vertices. The tet ...

; they share faces through which the silver ions diffuse. RbAg₄I₅ was proposed around 1970 as a solid electrolyte for batteries, and has been used in conjunction with electrodes of silver and of RbI₃. Its conductivity does not exhibit substantial variation with changes in

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

. Rubidium silver iodide family is a group of compounds and solid solutions that are isostructural with the RbAg₄I₅ alpha modification. Examples of such advanced superionic conductors with mobile Ag⁺ and Cu⁺

cation 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 convent ...

s include KAg₄I₅, NH₄Ag₄I₅, K_1−xCs_xAg₄I₅, Rb_1−xCs_xAg₄I₅, CsAg₄Br_1−xI_2+x, CsAg₄ClBr₂I₂, CsAg₄Cl₃I₂, RbCu₄Cl₃I_{2 and} KCu₄I₅.

References

{{rubidium compounds Metal halides Iodides Rubidium compounds Silver compounds Alkali metal iodides