Aging of electrolyte La0.88Sr0.12Ga0.82Mg0.18O3 − δ made using magnetic-pulse compaction

Ceramics of the La_0.88Sr_0.12Ga_0.82Mg_0.18O_{3 ? δ} solid electrolyte was obtained by magnetic-pulse compaction (MPC) of a powder synthesized using the self-propagating high-temperature synthesis technique with further sintering at 1380°C. Conductivity and its change in time were studied. It was shown that conductivity of fresh samples coincides with conductivity of ceramics obtained using the classical solid-phase synthesis. It was established that conductivity of electrolyte decreased by 18% during isothermal exposure at 700°C for 1 year.     

Fabrication of multilayer ceramic structure for fuel cell based on La(Sr)Ga(Mg)O<Subscript>3</Subscript>–La(Sr)Fe(Ga)O<Subscript>3</Subscript> cathode

Fabrication by co-sintering method of a multilayer pore-free electrode–electrolyte structure promising for use in solid-oxide fuel cell and its characteristics have been studied. A material with high ionic conductivity of La_0.88Sr_0.12Ga_0.82Mg_0.18O_3–δ (LSGM) served as electrolyte. The composite electrode was formed from a 1: 2 mixture of LSGM and LSFG (La_0.7Sr_0.3Fe_0.95Ga_0.05O_3–δ). The maximum temperature of the materials co-sintering ability is 1250°C. It was shown by the impedance spectroscopy that the polarization resistance of the LSGM–LSFG electrode is 0.14 Ω cm² at 800°C.     

Characteristics of the La0.6Sr0.4Fe0.8Co0.2O3 − δ electrode in contact with the lanthanum gallate-based electrolyte

Lowering the working temperature of solid oxide fuel cells (SOFCs) is the main trend in their development, which requires selection of materials for electrolyte and electrodes. A highly conducting lanthanum gallate-based electrolyte is a promising material for creating medium-temperature SOFCs. The electrochemical characteristics of the La_0.6Sr_0.4Fe_0.8Co_0.2O_{3 ? δ} cathode that contacted with the La_0.88Sr_0.12Ga_0.82Mg_0.18O_2.85 electrolyte subject to electrode formation temperatures have been investigated. It was found that at optimum bake-on temperatures of 1200–1250°C, the cathode polarization resistance at 800°C was ～0.08 Ohm cm², which is comparable to the world’s best achievements.     

Studying the O2, Metal/O2– (Solid Electrolyte) Electrode System on Model Electrodes: The Electrolyte Surface Layer Properties

A model cell that features a set of parallel platinum contacts adjacent to one another is studied by an impedance spectroscopy method. The characteristic linear size (width) of a contact is nearly 100 m. Even contacts are used as a working electrode and odd, as an internal reference electrode. The difference between electrode spectra, when measured relative to the latter and to a traditional reference electrode deployed at a distance, suggests that an expansion of the triple-phase boundary does exist and exceeds 0.3 mm and that electric properties of the electrolyte's surface layer differ from those of the bulk.     

Electrosynthesis of poly-o-diaminobenzene on the Prussian Blue modified electrodes for improvement of hydrogen peroxide transducer characteristics.

Electropolymerisation of nonconducting polymer, poly-(1,2-diaminobenzene) on the top of Prussian Blue (PB) modified electrode led to significant improvement of resulting hydrogen peroxide transducer selectivity and operational stability. The reported transducer retained 100% of response during 20 h under the continuous flow of 0.1 mM H(2)O(2), and thus improves the stability level in selective peroxide detection by one order of magnitude. The selectivity value of the PB-poly(1,2-DAB) based H(2)O(2) sensor in relation to ascorbate is approximately 600. No signals to acetaminophen and urate were investigated. PB-poly(1,2-diaminobenzene) modified electrode allows the detection of H(2)O(2) in the flow-injection mode down to 10(-7) M with the sensitivity 0.3 A M(-1) cm(-2), which is only two times lower compared to the uncovered PB based transducer.     

Model Gauze Electrode O2,Pt/O2–: Effect of the Cell's Pretreatment and the Single-Crystal Electrolyte Orientation

The polarization resistance of a model platinum gauze electrode in contact with a single-crystal electrolyte of doped zirconium dioxide is studied by impedance spectroscopy. Geometric characteristics of metal/electrolyte contact (contact area, triple-phase boundary length) are easily determined. The electrode pretreatment affects results of measurements in identical conditions. Cathodic and anodic polarizations increases its activity. The partial polarization resistance of a low-frequency relaxation process (R₂) alters jumpwise, which suggests that there exist an initial state and a state after a current treatment. During a prolonged storage, R₂ alters with time and tends to regain the initial state. The polarization resistance of the initial electrode depends on the electrolyte orientation. No such dependence is observed for the current-treated electrode.     

Studying the O2, Metal/O2– (Solid Electrolyte) Electrode System with Use of Model Electrodes: The Exchange Current Density Determination

Cells with model gold and platinum electrodes are studied by an impedance spectroscopy method. Distinguishing features of these electrodes are a large characteristic size of the metal/electrolyte contact (up to 100 m) and such well definable geometrical parameters as the length of triple-phase boundary (TPB) and the contact area. E. Shouler discovered that the electrolyte resistance, measured in an electrochemical cell, varies with the oxygen activity. Modern view is that this is connected with the TPB expansion. The expansion parameters determined here depend on the electrolyte prehistory and reach a few tens of micrometers. Specific (referred to a unit TPB length) values of polarization conductivities of both electrodes are obtained. Depending on the electrode prehistory, they amount to (2–6.5) × 10^–4 and (3–22)× 10^–4 S cm^–1 for Pt and Au, respectively, at 977°C in an oxygen atmosphere. The polarization conductivity, calculated per unit active area of electrolyte, is independent of the Pt electrode prehistory. Calculated exchange current densities are compared with radioisotope assay results.