The development of proton conductors has proceeded rapidly in recent years. A number of organic or inorganic materials show proton conductivities of ∼10⁻² S cm⁻¹ at temperatures below 100°C. However, although there is great current demand for proton conductors capable of operating in the temperature range of 100–400°C in practical applications, very few materials that can satisfy this demand have been reported to date. Acceptor-doped SnP₂O₇ are promising candidate materials because their proton conductivities reach >10⁻¹ S cm⁻¹ in the temperature range of interest. This paper presents an overview of the current status of acceptor-doped SnP₂O₇, highlighting the mechanism and kinetics of proton conduction and the development of electrochemical devices using these materials. New insights for proton insertion and conduction are proposed that use electrochemical techniques. Two approaches to designing SnP₂O₇-based composite electrolytes with good mechanical properties have also been developed for different operating temperatures. In addition, the benefits of intermediate-temperature operation using these materials are discussed in terms of practical applications, especially in fuel cells, exhaust sensors, and solid catalysts.

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For high temperature application, a planar SO₂ sensor using NASICON as an electrolyte and V₂O₅/WO₃/TiO₂ + Au or Pt as a sensing electrode was fabricated and investigated. In the case of Pt electrodes, the sensor showed the strange response in temperature range from 300–600°C. In the case of Au electrodes, the sensor showed a strange behavior at 300 and 400°C, while at 600°C the sensor showed good response to SO₂. The highest sensitivity with 80–83 mV/decade in the SO₂ range from 20 to 200 ppm was observed at 600°C, although offset shifting was observed in repeated measurements. The sensors showed the potential for good selectivity at 600°C in the case of Au electrodes. The fact that the electric potential difference of the sensor is strongly affected by the electrode materials may intend that the mechanism of the sensor is a mixed potential type.

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Asymmetric kinetics in the electrochemical charge–discharge reaction has been investigated in the two-phase coexistence system at LiFePO₄ positive electrodes for rechargeable Li ion batteries. The analyses of the electrochemical polarization profiles obtained by galvanostatic-pulse cycles reveals that nucleation and mass-transport is rate determining process for anodic and cathodic (charge and discharge) reaction, respectively, at high-rate conditions. We suggest that present two-phase system of LiFePO₄–FePO₄ forms core–shell type construction in each particle or agglomerate of particles, where LiFePO₄ prefer to reside at outer shell-region of particles maybe due to smaller interfacial energy with electrolytes.

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We investigated the selective metallization on Ag₂O-doped silicate glass under femtosecond laser irradiation after electroless plating. We found, as increasing the laser power, the width of the ablated groove increased from 2.5 to 7.5 µm, and then the resulted new surface could offer an active site for reduction of Cu cations, leading to corresponding plated Cu lines with widths from 7.4 to 25.4 µm. The mechanism was supposed as irradiation of the femtosecond laser (FL) on Ag₂O doped silicate glass surfaces result in the reduction of silver ions, and consequently, then the formation of silver atoms or even silver nanoparticles became the seeds for the next electroless plating process.

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LiCoO₂ is a popular positive electrode material for Li-ion secondary batteries. The perpendicular alignment of the interlayer of the LiCoO₂ lattice on the electrode contributes to easy access of Li-ions. In this study, we report the preparation of an oriented LiCoO₂ sheet using the conventional coating method followed by drying in a maximum 12 T strong magnetic field. We discuss the effect of the particle shape and viscosity of the paste on the degree of orientation. As a result, when the sheets are dried in a strong horizontal magnetic field, the electrochemical active planes of the LiCoO₂ are aligned perpendicular to the sheet surface.

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Low temperature sintering of α-cordierite ceramics with low coefficient of thermal expansion was attained using Li₂O–Bi₂O₃ sintering additive. High purity α-cordierite could be synthesized at 1270°C using high purity and fine amorphous silica, α-alumina and magnesium oxide powder mixture via the solid state reaction route. The mixture was calcined at 1240°C, pulverized, compacted, and at first sintered without sintering additive. High density and outstanding characteristics cordierite ceramics was obtained. However, sintering temperature reached 1430°C, which was extremely high. By adding 3 mass % of the additive, the sintering temperature could be lowered from 1430 to 1050°C. Its relative density reached 97%, its flexural strength, however, decreased from 243 to 120 MPa. Its thermal expansion coefficient (from R.T. to 800°C) decreased slightly from 1.8 × 10⁻⁶/K to 1.6 × 10⁻⁶/K. Its dielectric constant increased slightly from 4.9 to 5.2 accompanied with considerable increase in loss tangent from 1.3 × 10⁻⁴ to 6.1 × 10⁻⁴ at 14 GHz, which were, however, low enough at this high frequency range. These results indicated that the addition of Li₂O–Bi₂O₃ sintering additive had negligibly small effects on the properties of the sintered sample except mechanical properties and the loss tangent. These properties were found more excellent or at least comparable compared with the best properties previously reported and suitable for substrate materials on micro-electronic applications.

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