The vision of ionics

Materials with fast ionic motion will have a major impact on the solution of some of our largest problems in areas of environmental protection and energy-storage, -conversion and-savings. A large variety of upcoming technologies is described which may not or not as well become realized without ionic materials. These include sensors, high performance batteries, electrochromic windows and displays, fuel and water electrolysis cells, chemotronics, semiconductor ionics, electrocatalysis, thermoelectric converters and photogalvanic solar cells.     

Sol-gel ionics

The sol-gel synthesis of metal oxides offers new possibilities in the field of solid state ionics. The chemical design of molecular precursors allows a better control of the polymerization process so that taylor-made materials could be obtained. New hybrid organic-inorganic compounds exhibit high ionic conductivities and could be used as electrolytes. Oxide gels are actually particle hydrates. Water adsorption and dissociation at the oxide-water interface are responsible for their properties as ion exchangers or fast proton conductors. Colloidal particles are very small so that the large solid-liquid interface provides improved electrochemical properties which can be used for making reversible cathodes or electrochromic devices. The sol-gel deposition of thin coatings of large area could open the possibility to make multilayer micro-ionic devices.     

Medical applications of solid state ionics

Solid state ionic materials and devices are being used in medicine in many ways. A brief initial introduction to the materials, the devices and the pertinent electrophysiological and clinical aspects is presented. To exemplify the breadth of SSI material and device applications, an overview is given of three main areas: Biomedical applications of solid state power sources; biofuel cells; and iontophoretic and related devices used for controlled transdermal drug delivery and monitoring of physiological parameters.     

The applications of X-ray absorption spectroscopy in the study of solid state ionics

X-Ray absorption spectroscopy is a powerful method of determining local structures in condensed matter. This article reviews the applications of this technique in the study of solid state ionic materials. It begins with an outline of the principles and the experimental procedures followed by a brief overview of some of the recent developments. The bulk of the article is focused on a discussion of examples chosen to emphasise the kinds of problem that can be resolved using the technique. These include studies of local structure in perovskites-structured materials (BaLiF₃), proton conducting ceramics (CaZrO₃), oxygen ion conductors (BIMEVOX) and semiconducting gas sensors (SnO₂). Each system has been selected to show various facets of the technique in terms of the experimental method and data analysis. Paper presented at the 6th Euroconference on Solid State Ionics, Cetraro, Calabria, Italy, Sept. 12–19, 1999.     

Analysis of the frequency response of schottky junctions in solid-state ionics

The frequency response of a monocrystal with the presence of intrinsic space-charge layers beside two non-blocking electrodes is considered. It is assumed that only one type of charge carriers is mobile. For zero frequency an analytical expression of the impedance, similar to that of semiconductors devices, is obtained. At non-zero frequencies the representation of the electric field by a Fourier series leads to a simplification of the computational procedure. Numerical results are analysed on the basis of a perturbed charge density leading to an exact expression for the interfacial capacitance. Finally, the frequency dispersion of the interfacial capacitance is reported.