Showing papers by "Harry L. Tuller published in 2007"
TL;DR: In this article, thin-film composite electrodes with nanometric grains of platinum and yttria-stabilized zirconia (YSZ) were reactively sputtered onto single-crystal YTTria-Stabilized ZIRconia, and activation polarization resistance exhibited an activation energy of 13-15 eV and was found to have an approximate inverse dependence on microelectrode radius squared.
Abstract: Thin-film composite electrodes with nanometric grains of platinum and yttria-stabilized zirconia (YSZ) were reactively sputtered onto single-crystal yttria-stabilized zirconia The activation polarization resistance exhibited an activation energy of 13-15 eV and was found to have an approximate inverse dependence on microelectrode radius squared, consistent with, effectively, a mixed ionic-electronic conductive nature Area specific polarization resistances of less than 500 Ω cm 2 were achieved at 400°C in a dense thin-film electrode The attractiveness of these nanocomposite electrodes for use in microfabricated solid oxide fuel cells (SOFCs), of interest as portable power sources, is discussed
44 citations
TL;DR: In this article, photolithographically patterned platinum microelectrodes were created on yttria-stabilized zirconia (YSZ), and the electrodes, typically tens of microns across, were orders of magnitude greater in width than that reported for the triple phase boundary width.
39 citations
TL;DR: In this paper, the authors used defect and transport models to calculate the dependence of the partial ionic and electronic conductivities and the mass change for langasite as functions of temperature, dopant type and level and pO2.
Abstract: The electrical and gravimetric properties of langasite, La3Ga5SiO14, are related to its underlying defect and transport processes via previously developed predictive defect and transport models. These models are used here to calculate the dependence of the partial ionic and electronic conductivities and the mass change for langasite as functions of temperature, dopant type and level and pO2. Doping strategies devised for minimizing conductivity in langasite based on use conditions are described. For example, the required dopant level to achieve minimum conductivity and thus minimum electrical losses in acceptor-doped langasite is shown to depend on the operating pO2. Likewise intrinsic mass changes in langasite, dependent on dopant level, pO2 and temperatures, if high enough, can mask mass changes induced in active layers applied to langasite when used as a microbalance. For example, the model predicts that the dopant level in donor-doped langasite has less of an impact on intrinsic mass change due to external environmental changes when compared to acceptor-doped langasite. The models are also applied in defining acceptable operating limits needed to achieve and/or the design of properties for desired levels of microbalance resolution and sensitivity.
25 citations
TL;DR: In this paper, the authors present a review of methods of optimizing ionic conduction in solids and controlling the ratio of ionic to electronic conductivity in mixed conductors.
Abstract: Solid state ionic conductors are crucial to a number of major technological developments, notably in the domains of energy storage and conversion and in environmental monitoring (such as battery, fuel cell and sensor technologies). Solid state ionic membranes based on fast ion conductors potentially provide important advantages over liquid electrolytes, including the elimination of sealing problems improved stability and the ability to miniaturize electrochemical devices using thin films. This chapter reviews methods of optimizing ionic conduction in solids and controlling the ratio of ionic to electronic conductivity in mixed conductors. Materials are distinguished based on whether they are characterized by intrinsic versus extrinsic disorder, amorphous versus crystalline structure, bulk versus interfacial control, cation versus anion conduction and ionic versus mixed ionic–electronic conduction. Data for representative conductors are tabulated.
10 citations