This review represents the authors' view of the evolution of solid-state ionics over approximately the past 100 years. A brief history, introducing milestones of the development of this discipline, is followed by a short summary of the theory of ionic conduction in the bulk and the more recently developed theory of ionic conduction at interfaces. The central part of the article gives examples of ionic-conducting materials systems with structures ranging from one- to three-dimensional disorder. Important experimental techniques for analyzing ionic conduction, including alternating-current impedance spectroscopy, direct-current coulometry, and direct-current current-voltage measurements with blocking electrodes, are also summarized. The main technological applications, that is, batteries, solid-oxide fuel cells, electrochemical sensors, electrochromic windows, and oxygen-separation membranes, are reviewed. Finally, new concepts in solid-state ionics are presented, including the investigation of new materials (such as nanostructured phases), the study of boundaries (for example, using microelectrodes), the development of computational techniques, and the connections with other classes of materials (notably magnetic and semiconducting materials).

Solid‐State Ionics: Roots, Status, and Future Prospects

Multiple-junction structures were formed, on a microscopic scale, at room temperature, by the application of a strong electric field across originally homogeneous crystals of the ternary chalcopyrite semiconductor CulnSe2. After removal of the electric field, the structures were examined with electron beam-induced current microscopy and their current-voltage characteristics were measured. Bipolar transistor action was observed, indicating that sharp bulk junctions can form in this way at low ambient temperatures. The devices are stable under normal (low-voltage) operating conditions. Possible causes for this effect, including electromigration and electric field-assisted defect reactions, are suggested.

http://science.sciencemag.org/content/sci/258/5080/271.full.pdf

Room-Temperature, Electric Field-Induced Creation of Stable Devices in CulnSe2 Crystals

The recent literature dealing with the redox mechanism of the lead-acid cell positive electrode is reviewed. The basis electrochemistry of lead dioxide in its various polymorphic modifications and states of subdivision is considered in relation to the important aspects of electrode technology of which the major industrial application of the material is the conventional lead-acid cell. The proposed mechanism of the reduction (discharge) of lead dioxide in various acidic solutions are considered in relation to the present state of electrode kinetic theory. The reverse reaction by which lead dioxide is formed and the parasitic intrusion of the self discharge are dealt with as a precursor to the total cyclic process. It is concluded that in a number of respects the mechanisms proposed do not adequately represent the totality of the experimental observations. Such shortcomings are emphasized and extensions to present research are proposed.

The lead dioxide electrode

Festkorper mit geeigneter Struktur und geeigneten elektronischen Eigenschaften vermogen bei Raumtemperatur uber reversible Redoxreaktionen Einlagerungsverbindungen zu bilden; diese Reaktionen sind mit topotaktischen Elektronen/Ionen-Transferprozessen verbunden. Der Bereich der bekannten Wirtsgitter erstreckt sich von anorganischen Festkorpern unterschiedlicher Strukturdimensionalitat bis hin zu organischen Verbindungen mit Molekulgittern. Eine vergleichbare Vielfalt besteht hinsichtlich der Gastspezies; in Abhangigkeit vom Wirtsgittertyp konnen sowohl kleine Ionen (Metallkationen, Protonen) als auch grose anorganische und organische Molekulionen aufgenommen werden. Das systematische „Masschneidern” neuer stabiler und metastabiler Verbindungen, die gezielte Modifikation physikalischer Eigenschaften von Festkorpern sowie die technische Anwendung von Elektronen/Ionenleitern sind ein weites und interessantes Gebiet fur Grundlagenforschung und angewandte Forschung in einem interdisziplinaren Bereich, der Festkorperchemie und -physik, Molekulchemie, Elektrochemie und Grenzflachenwissenschaften einbezieht.

Reversible topotaktische Redoxreaktionen von Festkörpern durch Elektronen/Ionen‐Transfer

Semiconductors are key materials in modern electronics and are widely used to build, for instance, transistors in integrated circuits as well as thermoelectric materials for energy conversion, and there is a tremendous interest in the development and improvement of novel materials and technologies to increase the performance of electronic devices and thermoelectrics. Tetramorphic Ag10Te4Br3 is a semiconductor capable of switching its electrical properties by a simple change of temperature. The combination of high silver mobility, a small non-stoichiometry range and an internal redox process in the tellurium substructure causes a thermopower drop of 1,400 μV K−1, in addition to a thermal diffusivity in the range of organic polymers. The capability to reversibly switch semiconducting properties from ionic to electronic conduction in one single compound simply by virtue of temperature enables novel electronic devices such as semiconductor switches. Switching between n- and p-type conduction in a semiconductor can be done through doping. A fundamentally different behaviour has now been observed in Ag10Te4Br3, as a transition from ionic to electronic conduction is achieved simply by heating, which could be used for switches or in novel electronic devices.

Reversible switching between p- and n-type conduction in the semiconductor Ag10Te4Br3.

Measurements of chemical diffusion coefficients of mixed conducting solids using point electrodes-investigations on Cu2S

The decomposition of the mixed conducting low temperature phases of Ag2S and Cu2S by applying electrical potential differences between two metal electrodes has been investigated. The experimental method is based on the use of a chemically inert point electrode. It is demonstrated that the electrical resistance of mixed conducting solids measured at point electrodes is a sensitive quantity for the detection of the deposition of components or other phases with different stoichiometry during the decomposition process. — The results on Cu2S and Ag2S show a large difference in the stability behaviour of the two substances. The deposition of copper on Cu2S occurs at critical voltages which are up to 250 mV higher than expected from thermodynamic data. On the other hand, silver or sulfur respectively are deposited on Ag2S approximately at the expected voltages.

Stability Behaviour of Mixed Conducting Solids after Applying Electrical Potential Differences — Measurements with Point Electrodes on Ag2S and Cu2S

\"Devanathan cell\" / Palladium membrane / Lead dioxide layer / Hydrogen / Leaddioxide electrode Using a double cell (\"Devanathan cell\") whose partial cells were separated by a palladium membrane with a dense lead dioxide layer deposited on one side, it could be shown that hydrogen is able to diffuse easily through the Pb02. Furthermore it was found that hydrogen can dissolve in the lead dioxide coming from the palladium. This solubility ofhydrogen is important with regard to the electrochemical behaviour of a lead dioxide electrode.

Elektrochemische Untersuchungen zur Permeation und Löslichkeit von Wasserstoff in Bleidioxid

In der vorliegenden Arbeit wird der gleichzeitige Einflus won zwei Phasengrenzreaktionen auf die Kinetik der Sulfidierung won Silber im Schwefeldampf theoretisch und experimentell untersucht. Diese beiden Phasengrenzreaktionen sind 

ader Durchtritt won Silber durch die Phasengrenze festes Silber/festes Silbersulfid
bDie Anlagerung won Schwefel aus der Gasphase an Silbersulfid.


Fu beide Phasengrenzreaktionen lie- Ken Hemmungen vor, d. h. es treten an beiden Phasengrenzen Abweichungen vom thermodynamischen Gleichgewicht auf. Die Phasengrenzreaktionen lassen sich unabhangig voneinander mit elektro- chemischen Methoden unter Verwendung won Silberjodid als festem Hilfselektrolyten rnit praktisch reiner Ionenleitung - untersuchen. Die jeweiligen Reaktionsgeschwindigkeiten konnen dabei als Funktion des chemischen Potentials des Silbers im Silbersulfid gemessen werden. Aufgrund der Kenntnis der Phasengrenzreaktionen last sich die Geschwindigkeit der Sulfidierung won Silber im Schwefeldampf berechnen. Die berechneten Werte stimmen rnit gravimetrisch gemessenen gut uberein.

Einfluß von Phasengrenzreaktionen bei der Oxidation von Metallen Untersuchungen zur Sulfidierung von Silber in Schwefeldampf

An anticorrison protected small electric household water heating tank includes a metal tank having a passive anticorrosive layer provided on an inner wall thereof. A U-shaped electric immersion heating element is horizontally arranged in a lower region of the tank. A pair of electrodes are supplied with external current, one being an external current anode horizontally arranged above and perpendicular to the arms of the U-shaped heating element and the other being the tank itself. A reference electrode is also provided in the lower region of the tank. A potentiostat is connected to the reference electrode and tank for detecting the potential between the reference electrode and tank, for comparing the detected potential between tank and reference electrode to a reference voltage and for adjusting the current flow to the external electrodes to maintain an optimum potential between the tank and reference electrode. The reference electrode is of "Ag/AgCl" and is surrounded by a flow preventing sheathing which creates a zone of stagnant water about the reference electrode. An additional anode can be provided in the upper region of the tank and the current therethrough controlled by the potentiostat.

Hans Rickert

Papers

Measurements of chemical diffusion coefficients of mixed conducting solids using point electrodes-investigations on Cu2S

Stability Behaviour of Mixed Conducting Solids after Applying Electrical Potential Differences — Measurements with Point Electrodes on Ag2S and Cu2S

Elektrochemische Untersuchungen zur Permeation und Löslichkeit von Wasserstoff in Bleidioxid

Einfluß von Phasengrenzreaktionen bei der Oxidation von Metallen Untersuchungen zur Sulfidierung von Silber in Schwefeldampf

Water tank having electric heating element and cathodic corrosion protection