Ionic conductivities of solid CeO2:Y203 electrolytes were systematically investigated as a function of dopant concentration and sintering temperatures. The highest lattice conductivity occurred at 6–8% dopant concentration, and maximum grain boundary conductivity was observed at 10% dopant concentration. The sintering temperature was found to have a significant effect on the conductivities of the pellets. The samples sintered at lower temperatures (T≤140°C) showed higher grain boundary conductivity than those sintered at 150°C; this was found to be related to size-dependent-impurity segregation and precipitation at grain boundaries. The grain boundary conductivities as related to the microstructure are discussed by adopting different grain boundary models. Solute segregation and oxygen depletion at grain boundaries, which have been suggested to be responsible for the grain boundary resistivities in these samples, were examined by a microanalytical technique for small-grain-size samples.

We have prepared Y2O3 doped CeO2 thin films on various substrates using electron beam evaporation. Both polycrystalline and single crystal-like textured films were shown by x-ray diffraction and transmission electron microscopy analyses. AC impedance spectroscopy was used to study the electrical properties of the films. The ionic conductivities of the films are dominated by grain boundaries, and higher as compared to that of a bulk material having the same dopant concentration sintered at 1500°C. The grain boundary conductivities of the films were investigated with regard to grain size, grain boundary impurity segregation, space charge on grain boundaries, and grain boundary misorientations. The contribution of grai boundary misorientation to the resistance of the grain boundary is considered to be negligible with respect to those of the impurity layer and space-charge layers. The grain boundary resistance may originate from the oxygen vacancy depletion in the space-charge layers.

M2O3-CeO2(M=Sm, La) system is one of the most interesting of fluorite oxides since the oxide ionic conductivity of it is higher than that of yttria-stabilized zirconia. In this study, the effective index for the improvement of ionic conductivity in CeO2 systems was defined using information regarding ionic radii and the level of oxygen vacancies from the perspective of crystallography. It is assumed that the M2O3 CeO2 based oxides approach the ideal fluorite structure for fast ionic conduction when the effective index increases toward 1. A small amount of alkali- or alkali-earth doped M2O3-CeO2 (M=Sm, La) solid solutions were prepared based on this effective index. The oxide ionic conductivity increased with an increase of this effective index. (La0.75Sr0.2Ba0.05)0.175 Ce0.825 O1.89 that had high effective index, showed high oxide ionic conductivity over the order of magnitude in comparison with 8mol% yttria-stabilized zirconia. Moreover, the oxygen partial pressure dependence of oxide ionic conductivity of M2O3-CeO2(M=Sm, La) solid solutions was improved by the increasing effective index. The utility of this effective index, for improvement of the electrical properties in fluorite CeO2 based materials, was investigated.

Fast Cu+-conducting ceramics containing NASICON-type CuTi2(PO4)3 and Cu3 (PO4)2 phases, which three-dimensionally interlock with each other, has been successfully prepared by the controlled crystallization of glass in the Cu-Ti-P-O system. The electrical conductivity of the glass-ceramic was ∼3×10−4Scm−1 at 300°C. The obtained glass-ceramics was applied to an oxygen-concentration cell operating at low temperature such as 100°C. The electromotive force (EMF) of the sensor showed good Nemstian response. The mechanism for O2 sensing is discussed in terms of the redox reaction between Cu+ ion in the dense glass-ceramic and O2 gas.

The realization of a trivalent ion conduction in solids was successful by selecting the Sc2(WO4)3-type structure from the consideration of the mobile trivalent cations and the structure which decreases the electrostatic interaction between the migrating trivalent ionic species and the framework structure as much as possible. Among the rare earth tungstates, Sc2(WO4)3 (σ600°C=6.5× 10−5 S'cm−1, Ea=44.1 kJ.mo−1) was found to hold the most suitable size for the trivalent ion migration in the relation between the mobile ion size and the lattice volume. The ion conducting characteristics of rare earths were studied by means of both the polarization and dc electrolysis techniques. The mobile species was demonstrated to be the trivalent ions in the Sc2(WO4)3-type structure. By the dc electrolysis, the mobile ion species was definitely identified to be the trivalent ions in the Sc2(WO4)3-type tungstates. In addition, the demonstration of a macroscopic Al3+ ion conduction in the tungstate structure was directly accomplished.

Comparisons are made between the material requirements for supercapacitor electrodes and the cathode of a lithium-ion battery. The performances of the battery cathodes Li1+xFe2(SO4)2(PO4) and Li1+5 VMoO6 are compared to those for supercapacitor electrodes operating with 5.3 M H2SO4, Nafion 117, or 2 M KCl aqueous solution at pH 6.7. The use of a KCl aqueous electrolyte at mild pH allows stabilization of amorphous, hydrated electrode materials such as a-MnO2nH2O that are not stable in 5.3 M H2SO4 or with Nafion 117. However, the larger K+ ion appears to reduce by a factor of three the theoretical capacity attainable with H+ ions.

λ–Ce2S3, like many other cerium containing chalcogenides, presents a strong absorption in the visible spectra in relation with the CeIII-4fl → CeIII-5d1 electronic transition taking place at around 1.9 eV. This transition energy, that induces a red hue for the phase, can be increased by changing the nature of the Ce-S bonding, in particular through an enhancement of its ionicity. This can be made by inserting/substituting some alkali metal ions in the structure of λ-Ce2S3. The sodium-doped λ-Na3/8Ce15/2S3 phase for instance undergoes a CeIII-4f1 → Cemi-5d1 transition energy increase of 0.12 eV. This shift is sufficient to modify substantially the pigment properties of the material and it has been mainly related to the narrowing of the electronic bands. In CePS4, Ce2SiS5, Ce4Si3S12and Ce6Si4S17, strong covalent bondings enhance the ionic Ce-S bond through inductive effect, leading to a CeIII-4f1 → CeIII-5d1 electronic transition in the blue (Eg - 2.5 eV) hence the yellow hue of these materials. Within the Ce-Si-S family, small differences may be attributed to difference in the [CeSx] and [SiS4] polyhedra bonding. The Ce3(TS4 )2X family (X = Cl, Br, I, T = Si, Ge) does not show pigment properties because of the Ce-X bond inducing a more Ce-S ionic character (in particular when X = Br, I) and thus a higher gap that is found in the near ultraviolet. On the other hand, the phases present an important room temperature blue fluorescence.

In this paper we report the fabrication of high reflectivity modulation electrochromic Windows (ECW's) which have exhibited a colored state reflectivity of more than 50% for the wavelength range of 1 to 2.5 µm with an average bleached state reflectivity of 20%. The transmissivity of these ECW's in the colored state was less than 5% and in the bleached state it averaged 60%. The materials employed were tungsten oxide (nominally WO3) for the first electrochromic electrode, lithium cobalt oxide (nominally LiCoO2) for the second, complementary, electrochromic electrode, lithium phosphorus oxynitride (Lipon) for the ionic conductor (electrolyte), and indium tin oxide (ITO) and indium oxide (In2O3) for the two transparent electronic conductors. The predicted and measured reflectivity of the ECW's were influenced by the first transparent conductor (TM) in relation to its thickness and optical properties. Devices without a TC1 exhibited the highest reflectivity modulation, It was also concluded that two of the main limitations to the degree of reflectivity modulation attainable with the ECW's were lithium insertion into TC1 and electronic transport through the electrolyte.

Polymer electrochemical cells have been reported to emit light. The current and light output increase rapidly with voltage, apparently beyond 2V. The polymer is an ionic conductor as well as an electronic (electron/hole) conductor, i.e. a mixed ionic-electronic conductor (MIEC).

The I-V relations are explained here to be those of an MIEC of a particular defect model placed between two ion blocking electrodes. This MIEC defect model assumes a large concentration of mobile ions and small concentrations of electrons and holes. A p and an n region are formed in the MIEC. However, there is no space charge within the MIEC and it stays neutral. The resulting I-V relations are exponential. A good fit to the experimental data is obtained when electrode over-potential and heating of the polymer under current are taken into consideration.

The fabrication of thin-film batteries has been achieved for more than a decade (Energizer1, Oak Ridge2, Seoul National Univ.3). The inventor of the process was K. Kanehori(ndeI u 1) The processes utilized; sputtering, vapor deposition, solvent coating of electrolyte, have succeeded in laboratory trials in making working cells. No large commercial process nor application has developed to date though pilot plant capability exists4. Performance characteristics of microbatteries are sufficient to easily power micro-sensors and CMOS microelectronics. On chip carrier power capability could be realized. The materials of today's microbattery are detrimental to silicon technology which can be a draw back to commercialization. New materials and processes need to be investigated.

Li-Alloy/FeS2 thermal batteries are the predominant thermal battery chemistry today. Conventional electrodes are fabricated by cold pressing of powders. A better means of providing thin electrodes would dramatically increase volumetric and gravimetric energy densities and cost efficiency of thermal batteries. In this study, experiments were conducted on fabricating the cathode via high-velocity oxygen-fuel (HVOF) and dc-arc plasma thermal spray technique. The deposited films were characterized by cross-section examination using Scanning Electron Microscopy (SEM) and X-ray Diffraction. The thermal decomposition of pyrite was suppressed by a proprietary additive. The electrochemical test results showed that pyrite cathodes prepared by dc-arc plasma spraying with additives demonstrated better performance compared traditional pressed-powder electrodes.

Pd, Pt and ZrO2-Pt films were prepared by metal organic chemical vapor deposition (MOCVD) as electrodes for zirconia solid electrolyte and their electrochemical properties were examined by impedance spectroscopy. Carbon containing films (Pt-C and Pd-C) consisted of agglomerated fine particles (2-5 nm in diameter) exhibit higher electrode conductivities than that of conventional Pt paste electrodes at temperatures below 873 K. The sintering of the fine particles and/or oxidation of impurity carbon or Pd spoil their electrochemical performance. On the other hand, two-phase ZrO2-Pt films show promise as electrode material for zirconia electrolyte at low temperatures (below 973 K) because of their higher conductivity than Pt paste electrodes and their thermal stability.

Polyaniline, aniline and o-NO2-aniline copolymer were synthesized using (NH4)2S2O8 as oxidant in 1 M HCl water solution. By means of IR, Raman spectroscopy, gravimetric and microanalysis it was confirmed that the obtained product is oxydized emeraldine. We developed Mg|2 M MgCl2(H2O + CH3) (3:1)| co-polymer (polyaniline) prismatic-type cells. The highest specific charge and energy were observed for cell with co-polymer AN:o-NO2-AN (8:2) which were 420.74 Ah kg−- and 424.95 Wh kg−-, respectively.